Display device

ABSTRACT

To improve an image quality of an organic EL display by utilizing characteristics of a dual emission type organic light emitting element. A display device includes a first substrate over which a plurality of organic light emitting elements are provided and a second substrate over which an organic light emitting element is provided. The first and second substrates are facing each other. At least either the organic light emitting elements provided over the first substrate or the organic light emitting element provided over the second substrate emit/emits light toward both surfaces of the first or second substrate. Light emitting regions of the organic light emitting elements provided over the first substrate are overlapped with a light emitting region of the organic light emitting element provided over the second substrate as seen from the second substrate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device including an organiclight emitting element. In particular, the present invention relates toa display device (an organic EL display) including a light emittingelement having an organic compound (an organic light emitting element)which emits light by being applied with electronic field. Moreover, thepresent invention relates to an electronic appliance using such adisplay device for a display portion.

2. Description of the Related Art

An organic light emitting element has a structure in which a layercontaining an organic compound (an organic light emitting material)which generates electroluminescence by being applied with electric field(hereinafter, referred to as an organic compound layer), is interposedbetween a pair of electrodes (a first electrode and a second electrode).The organic light emitting material is classified into a material whichcan convert energy upon returning to a ground state from a singletexcited state into light emission (a fluorescent material) and amaterial which can convert energy upon returning to a ground state froma triplet excited state into light emission (a phosphorescent material).

A display device including such an organic light emitting element (anorganic EL display) has characteristics of high response speed suitablefor movie display, requiring low driving voltage, and consuming lesspower, and therefore, the display device has been attracting attentionas a next generation display for a cellular phone, a portableinformation terminal, or the like.

Differing from a liquid crystal display device, the organic EL displayemits light by itself, and therefore, it has a feature of good viewingangle. Therefore, the organic EL display is more suitable as a displayused in the open air than a liquid crystal display so that various usesof the organic EL display have been proposed.

An organic light emitting element which is formed over a lighttransmitting substrate and emits light from both sides of the lighttransmitting substrate (hereinafter, referred to as a dual emission typeorganic light emitting element) has been known (e.g., see patentdocument 1). This dual emission type light emitting element has afeature of emitting light toward the both sides of the substrate, andtherefore, there has been an expectation of widespread application ofthe dual emission type light emitting element by utilizing such afeature.

-   [Patent Document 1]: Japanese Patent Application Laid-Open No.    2004-265691

Further, the patent document 2 discloses a display device which displaysfull color images by attaching panels including dual emission typeorganic light emitting elements which emits different colors of light toeach other such that light emitting regions of the organic lightemitting elements provided over each panel are not overlapped with eachother as seen from a viewer side.

-   [Patent Document 2]: Japanese Patent Application Laid-Open No.    2005-71693

An object of the present invention is to provide a display device whichutilizes the above mentioned features of a dual emission type organiclight emitting element. Another object of the present invention is toimprove image quality of an organic EL display by utilizing a dualemission type organic light emitting element. In order to improve theimage quality, concretely, the following three problems can be given.

First, a problem of controlling brightness of a displayed image can begiven. Suitable brightness of an organic EL display device is differedin a case of using the organic EL display device in a bright-lightlocation such as an outdoor location and in a case of using it in doors.Therefore, it is necessary to control brightness of the display devicedepending on brightness of a location of use.

Next, a problem of improving chromaticity can be given. For example,when color display with red (R), green (G), and blue (B) is performed,only colors within a triangle of a chromaticity coordinate of red (R), achromaticity coordinate of green (G), and a chromaticity coordinate ofblue (B) in a chromaticity diagram, have been expressed, and therefore,there has been a limitation in a range of colors which can be expressed.If the range of colors which can be expressed, can be more widened, thenumber of colors to be expressed can be increased so that moremicroscopic and realistic images can be displayed.

Furthermore, a problem of balance of colors can be given. It has beenknown that visibility is differed depending on colors. The visibilityindicates sensitivity of the eye to light. A yellow-green wavelength inthe vicinity of 555 nm shows highest visibility. As being shifted toshorter wavelengths than 555 nm, the visibility is reduced. Meanwhile,as being shifted to longer wavelengths than 555 nm, the visibility isreduced. Accordingly, the visibility of green light is higher than thevisibility of red light and the visibility of blue light. Thus, it isnecessary to balance the colors depending on the visibility.Furthermore, there is also a problem that a blue organic light emittingelement has lower luminance than red and green organic light emittingelements, and therefore, it is also necessary to balance the luminanceof red, green, and blue light.

The present invention is made in view of the above described problems.

In an aspect of the present invention, a display device includes a firstsubstrate over which an organic light emitting elements is provided, anda second substrate over which an organic light emitting element isprovided, wherein the first substrate and second substrate are providedto face each other, at least either the organic light emitting elementprovided over the first substrate or the organic light emitting elementprovided over the second substrate emits light toward both surfaces ofthe substrate, and a light emitting region of the organic light emittingelement provided over the first substrate and a light emitting region ofthe organic light emitting element provided over the second substrateare placed such that they are at least partly overlapped with each otheras seen from a viewer side.

In order to form an organic light emitting element which emits lighttoward both sides of a substrate over which the organic light emittingelement is provided, a first electrode and a second electrode of theorganic light emitting element may be formed using transparentconductive films. Accordingly, in the above described structure, thephrase “at least either the organic light emitting element provided overthe first substrate or the organic light emitting element provided overthe second substrate emits light toward both surfaces of the substrate”indicates that a first electrode and a second electrode of at leasteither the organic light emitting element provided over the firstsubstrate or the organic light emitting element provided over the secondsubstrate are formed using a transparent conductive film.

Note that, the first electrode of the organic light emitting element isplaced closer to the substrate over which the organic light emittingelement is provided than the second electrode of the organic lightemitting element. Thus, in the pair of electrodes of each organic lightemitting element provided over the first substrate, the electrode beingcloser to the first substrate is the first electrode.

In the above mentioned structure, a first organic light emitting elementis provided over the first substrate, a second organic light emittingelement, a third organic light emitting element, and a fourth organiclight emitting element are provided over the second substrate, and onepixel includes the first to fourth organic light emitting elements.

In the above mentioned structure of the present invention, a firstorganic light emitting element is provided over the second substrate, asecond organic light emitting element, a third organic light emittingelement, and a fourth organic light emitting element are provided overthe first substrate, and one pixel includes the first to fourth organiclight emitting elements.

In the above mentioned structure of the present invention, a firstorganic light emitting element and a second organic light emittingelement are provided over the first substrate, a third organic lightemitting element and a fourth organic light emitting element areprovided over the second substrate, and one pixel includes the first tofourth organic light emitting elements.

Further, in the present invention, the first to fourth organic lightemitting elements emit different colors of light from one another.

In the above mentioned structure of the present invention, a firstorganic light emitting element, a second organic light emitting element,and a third organic light emitting element are provided over the firstsubstrate, a fourth organic light emitting element, a fifth organiclight emitting element, and a sixth organic light emitting element areprovided over the second substrate, and one pixel includes the first tosixth organic light emitting elements.

Further, in the present invention, the first to third organic lightemitting elements emit different colors of light form one another.

Furthermore, the first to sixth organic light emitting elements emitdifferent colors of light form one another.

That is, in the above mentioned structure of the present invention, twocolored or three colored organic light emitting elements selected fromfour to six colored organic light emitting element of red, green, andblue organic light emitting elements and one to three colored organiclight emitting elements selected from red, green, blue, a complementarycolor of red, a complementary color of green, a complementary color ofblue, and white, are provided over the first substrate, and the rest ofthe four to six colored organic light emitting elements is/are providedover the second substrate.

Further, various kinds of combinations of organic light emittingelements provided over the first substrate and the second substrate canbe given. In relation to the combination of organic light emittingelements provided over the first substrate and the second substrate, thefollowing first to fourth structures of the present invention will bedescribed in more detail.

In the first structure of the present invention, red, green, blue, andwhile organic light emitting elements are provided over a firstsubstrate or a second substrate. That is, one pixel includes the fourcolored, i.e., red, green, blue, and while organic light emittingelements.

Note that, in the present specification, a minimum unit required fordisplaying an image is referred to as a pixel, and the pixel includes aplurality of dots. For example, when an image is displayed using threecolors of red, green, and blue, one pixel is constituted by threedifferent colored dots, i.e., a red dot, a green dot, and a blue dot asone set.

Therefore, it can be said that in the first structure of the presentinvention, one pixel includes a red dot, a green dot, a blue dot, and awhite dot.

As the first structure of the present invention, for example, an examplein which red, green, and blue organic light emitting elements areprovided over one of the first substrate and the second substrate,whereas a while organic light emitting element is provided over theother substrate, can be given.

Providing the white organic light emitting element over the substratedifferent from the substrate over which the red, green, and blue organiclight emitting elements are provided makes it possible to improvebrightness of an entire display screen of a display device.

When an organic EL display is used as a display portion of an electronicappliance used in the open air and in doors regardless of location suchas a cellular phone and a portable information terminal, if brightnessof a display screen is not suitably controlled in accordance withsurrounding brightness, visibility is degraded. In this case, byincreasing luminance of only the white organic light emitting elementprovided over the substrate different from the other substrate overwhich the red, green, and blue organic light emitting elements areprovided, the brightness of only the display screen can be improved.

Since the substrate having only the white organic light emitting elementis provided separately from the substrate having the red, green, andblue organic light emitting elements for performing color display, theluminance of the while organic light emitting element can be changedindependent from the red, green, and blue organic light emittingelements. Accordingly, the brightness of the display screen can beeasily controlled.

Further, when white color is displayed on a conventional organic ELdisplay which can perform color display, red, green, and blue organiclight emitting elements emit light and three colors of light emittedfrom the organic light emitting elements are mixed to be while light.However, in the structure of the present invention in which a substratehaving red, green, and blue organic light emitting elements and asubstrate having a white organic light emitting element are overlappedwith each other, only the white organic light emitting element emitslight while the red, green, and blue organic light emitting elementsemit no light so as to display white color. Therefore, power consumptioncan be more reduced as compared to the case of displaying white color bymaking the red, green, and blue organic light emitting elements emitlight.

Note that, the arrangement of the red, green, blue, and while organiclight emitting elements may, for example, be either a case A or a case Bas follows.

The case A: one dot of a white organic light emitting element isprovided over a second substrate such that it faces a region where onedot of a red organic light emitting element, one dot of a green organiclight emitting element, and one dot of a blue organic light emittingelement are provided over a first substrate.

The case B: dots of white organic light emitting elements arerespectively provided at positions over a second substrate correspondingto regions over the first substrate where a dot of a red organic lightemitting element, a dot of a green organic light emitting element, and adot of a blue organic light emitting element are provided over the firstsubstrate. Specifically, one dot of the white organic light emittingelement is provided over the second substrate such that it faces the onedot of the red organic light emitting element provided over the firstsubstrate, another one dot of the white organic light emitting elementis provided over the second substrate such that it faces the one dot ofthe green organic light emitting element provided over the firstsubstrate, and another one dot of the white organic light emittingelement is provided over the second substrate such that it faces the onedot of the blue organic light emitting element provided over the firstsubstrate.

In the case B, it is possible to independently control luminance of thewhite organic light emitting elements, which are provided at thepositions corresponding to each light emitting region of the red, green,and blue organic light emitting elements provided over the firstsubstrate. Therefore, red, green, and blue colors can be respectivelycontrolled. That is, for example, when only the white organic lightemitting element provided at the position corresponding to the redorganic light emitting element emits light, the white emission and redemission is mixed to exhibit pink emission while green emission and blueemission can be exhibited as they are, and hence, reproducibility ofcolors can be improved.

An example of providing the red, green, and blue organic light emittingelements over the first substrate while providing the white organiclight emitting element(s) over the second substrate are described ineach of the cases A and B. Alternatively, the red, green, and blueorganic light emitting elements provided over the first substrate andthe white organic light emitting element(s) provided over the secondsubstrate can be counterchanged. That is, the white organic lightemitting element(s) may be provided over the first substrate whereas thered, green, and blue organic light emitting elements may be providedover the second substrate.

A structural example in which only the white organic light emittingelement(s) is/are provided over one of the first and second substratesin each of the above described examples. Alternatively, any one of red,green, and blue organic light emitting elements may be provided over thesubstrate having a white organic light emitting element, whereas othertwo colored organic light emitting elements except for the organic lightemitting element provided over the same substrate as the white organiclight emitting element, may be provided over the other substrate. Thatis, for example, red and green organic light emitting elements may beprovided over any one of a first substrate and a second substrate, andblue and white organic light emitting elements may be provided over theother substrate.

In a structure in which a white organic light emitting element and anyone of red, green, and blue organic light emitting elements are providedover either a first substrate or a second substrate and the remainingtwo colored organic light emitting elements among the red, green, andblue organic light emitting elements (two colored organic light emittingelements other than the one of the red, green, and blue organic lightemitting elements provided over the one of the first and secondsubstrates) are provided over the other substrate, when areas of lightemitting regions of the red and blue organic light emitting elements areset larger than an area of a light emitting region of the green organiclight emitting element, it is possible to balance the red, green, andblue colors of light. This is because the visibility of the red and bluelight is lower than that of the green light.

Further, since the two colored organic light emitting elements areprovided over each of the first and second substrates, the number ofelements required for driving the organic light emitting elementsprovided for each dot can be reduced as compared to a case of providingthree colored organic light emitting elements over a substrate whilehaving the same number of pixels, and therefore, aperture ratio can beimproved.

In the second structure of the present invention, red, green, and blueorganic light emitting elements and one to three colored organic lightemitting element(s) whose color(s) is/are selected from a complementarycolor of red, a complementary color of green, and a complementary colorof blue, are provided over either a first substrate or a secondsubstrate. That is, one pixel includes four to six colored organic lightemitting elements with a combination of the red, green, and blue and oneto three colors selected from the complementary colors of red, green,and blue.

As the second structure of the present invention, for example, it ispossible to give an example in which red, green, and blue organic lightemitting elements are provided over one of a first substrate and asecond substrate, whereas one to three colored organic light emittingelement(s) selected from the organic light emitting elements of thecomplementary color of red, the complementary color of green, and thecomplementary color of blue, is/are provided over the other substrate.

The complementary color of red is blue-green (cyan), the complementarycolor of blue is yellow, and the complementary color of green isred-purple (magenta). By forming organic light emitting elements havingthese colors, colors which cannot be expressed by only red, green, andblue can be expressed, thereby widening the range of colors to beexpressed and largely improving reproducibility of colors.

Note that, it is not necessary to form all complementary colors oforganic light emitting elements with respect to red, green, and blue.The kinds or the number of colors of organic light emitting elementsprovided over the second substrate can be changed in accordance withquality of an image to be displayed. That is, one to three colors may beselected from the complementary colors of red, green, and blue inaccordance with quality to be required.

Although the structural example in which the red, green, and blueorganic light emitting elements are provided over either the firstsubstrate or the second substrate, is described above, the presentinvention is not limited thereto. Alternatively, two colored organiclight emitting elements selected from red, green, and blue organic lightemitting elements may be provided over one of first and secondsubstrates, and a one colored organic light emitting element, which is aremaining organic light emitting element of the red, green, and blueorganic light emitting elements, and a one colored organic lightemitting element or two colored organic light emitting elements whosecolor(s) is/are selected from the complementary colors of red, green,and blue, may be provided over the other substrate.

Since the visibility of red and blue light is lower than that of greenlight, when areas of light emitting regions of the red and blue organiclight emitting elements are set larger than an area of a light emittingregion of the green organic light emitting element, it is possible tobalance the red, green, and blue colors.

As such a structural example, the following example can be given: a redorganic light emitting element is provided over a first substrate; ablue organic light emitting element is provided over a second substrate;a green organic light emitting element is provided over either the firstsubstrate or the second substrate; a one colored organic light emittingelement selected from complementary colors of red, green, and blue isprovided either the first substrate or the second substrate; and areasof light emitting regions of the red and blue organic light emittingelements are set larger than an area of a light emitting region of thegreen organic light emitting element.

As compared to a case where three colored organic light emittingelements are provided over a substrate while having the same number ofpixels provided over the substrate, when two colored organic lightemitting elements are provided over each of the first and secondsubstrates, the number of elements required for driving the organiclight emitting elements provided in each dot can be reduced, making itpossible to improve aperture ratio.

Further, in the second structure of the present invention, emissioncolors of organic light emitting elements may be any colors which canwiden a range of a triangle of a chromaticity coordinate of red, achromaticity coordinate of green, and a chromaticity coordinate of blue,in addition to the complementary colors of red, green, and blue.Therefore, an organic light emitting element which emits light having achromaticity coordinate outside of the triangle of the chromaticitycoordinate of red, the chromaticity coordinate of green, and thechromaticity coordinate of blue, may be used. Therefore, one colored tothree colored organic light emitting element(s) which emits/emit a colorof light having a chromaticity coordinate outside of the triangle of thechromaticity coordinates of red, green, and blue, may be provided as asubstitute for the complementary colors of red, green, and blue.

In the third structure of the present invention, red, green, and blueorganic light emitting elements are provided over each of a firstsubstrate and a second substrate. Specifically, one pixel includes red,green, and blue organic light emitting elements provided over the firstsubstrate and red, green, and blue organic light emitting elementsprovided over the second substrate.

In the third structure of the present invention, when the organic lightemitting elements provided over the first substrate and the organiclight emitting elements provided over the second substrate areoverlapped with one another such that the same colored organic lightemitting elements are overlapped with one another, display can beperformed at more higher luminance. Accordingly, more gray scales can beexpressed.

Further, in this case, when light emitting regions of the same coloredorganic light emitting elements are at least partly overlapped with oneanother, display can be performed at higher luminance. However, it ispreferable that overlapping areas of the different colored organic lightemitting elements be increased so as to prevent reduction in apertureratio. That is, when light emitting regions of the organic lightemitting elements provided over the first substrate are overlapped withlight emitting regions of the organic light emitting elements providedover the second substrate at almost the same positions as seen from aviewer side, the highest aperture ratio can be obtained.

In the third structure of the present invention, when the light emittingregions of the different colored organic light emitting elementsprovided over the first and second substrates are overlapped with oneanother as seen from a viewer side, image resolution performance can beimproved.

Note that, in this case, when the light emitting regions of thedifferent colored organic light emitting elements are at least partlyoverlapped with one another, the image resolution performance can beimproved. However, it is preferable that overlapping areas of thedifferent colored organic light emitting elements be increased so as toprevent reduction in aperture ratio. That is, when the light emittingregions of the organic light emitting elements provided over the firstsubstrate are overlapped with the light emitting regions of the organiclight emitting elements provided over the second substrate at almost thesame positions as seen from a viewer side, the highest aperture ratiocan be obtained.

In the fourth structure of the present invention, red, green, and blueorganic light emitting elements are provided over a first substrate, andanother blue organic light emitting element is provide over a secondsubstrate. Specifically, one pixel includes the red, green, and blueorganic light emitting elements provided over the first substrate andthe blue organic light emitting element provided over the secondsubstrate.

Since a blue organic light emitting element has low luminance, theluminance of blue emission can be compensated by forming another blueorganic light emitting element over the second substrate, making itpossible to improve balance of luminance of red, blue, and green.

In the above mentioned fourth structure, a white organic light emittingelement may also be provided over the second substrate over which theblue organic light emitting element is provided. By providing the whiteorganic light emitting element over the second substrate, luminance ofblue emission can be compensated and brightness of a display screen canbe controlled.

In the fourth structure, one or two colored organic light emittingelements selected from complementary colors of red, green, and blue mayalso be provided over the second substrate over which the blue organiclight emitting element is provided. By providing one or two coloredorganic light emitting elements selected from the complementary colorsof red, green, and blue, luminance of blue emission can be compensatedand a range of colors to be expressed can be widened.

There are two ways of layout methods of the first substrate and thesecond substrate of the display device according to the presentinvention described above.

As a first layout method, a surface of the first substrate over which anorganic light emitting element is formed and a surface of the secondsubstrate over which an organic light emitting element is formed areattached to each other so as to face each other.

In accordance with the layout, the second substrate serves as a countersubstrate with respect to the first substrate whereas the firstsubstrate serves as a counter substrate with respect to the secondsubstrate. Therefore, the organic light emitting elements can be sealedwith only the first and second substrates. Accordingly, the displaydevice can have almost the same thickness as a normal display device inwhich an organic light emitting element is formed only over onesubstrate and the substrate is sealed with a counter substrate.

As a second layout method, a surface of the first substrate over whichan organic light emitting element is formed is attached to a surface ofthe second substrate which is opposite to the other surface of thesecond substrate over which an organic light emitting element is formed.

In the second layout method, the second substrate serves as a countersubstrate with respect to the first substrate. Thus, the first substratecan be sealed with the second substrate. However, the second substrateis not sealed with the first substrate. Therefore, a third substrate isprovided to face the surface of the second substrate over which theorganic light emitting element is formed so as to seal the secondsubstrate with the third substrate.

Accordingly, the organic light emitting elements can be sealed with lessnumber of substrates in the case of the first layout method as comparedto the second layout method, so that the first layout method requireslower cost. Moreover, a thickness of a panel formed by attaching thesubstrates can be more reduced in the first layout method as compared tothe second layout method, and hence, the first layout method is morepreferable.

Further, as a method for attaching the first and second substrates toseal the organic light emitting elements, various known methods can beemployed, for example, the first and second substrates are sealed with asealant in a sheet-form, a solid sealing material is applied to anentire surface of one of the first and second substrates to be attached,or a sealant is only applied to the circumference of the substrate and afiller is filled between the substrates.

When air does not exist between the first and second substrates by usingthe method in which a solid sealing material is applied to an entiresurface of the substrates to be attached, light extraction efficiencycan be improved.

Structures of the first and second layout methods of the first andsecond substrates will be respectively described in more detail below.

In the first layout method, the following three cases 1, 2, and 3 can bethought. In the case 1, the first and second substrates are lighttransmitting substrates, and organic light emitting elements providedover the first and second substrates emit light toward both sides ofeach substrate. In the case 2, the first substrate is a lighttransmitting substrate and an organic light emitting element providedover the first substrate emits light toward both sides of the firstsubstrate, whereas an organic light emitting element provided over thesecond substrate emits light toward a surface of the second substrateover which the organic light emitting element is provided, i.e., towardthe first substrate. In the case 3, the second substrate is a lighttransmitting substrate and an organic light emitting element providedover the second substrate emits light toward both sides of the secondsubstrate, whereas an organic light emitting element provided over thefirst substrate emits light toward a surface of the first substrate overwhich the organic light emitting element is provided, i.e., toward thesecond substrate.

In the case 1, display screens are formed over both of the first andsecond substrates, and an image recognized on the display screen formedover the first substrate is a mirrored image of an image recognized onthe display screen formed over the second substrate. Further, since thefirst and second substrates are the light transmitting substrates, thedisplay screens are formed over the first and second substrates while aviewer can see the view beyond the first and second substrates.

Further, by providing polarizing plates over the first and secondsubstrates, it is possible to prevent a viewer from seeing the viewbeyond the first and second substrates on both of the display screenformed over the first substrate and the display screen formed over thesecond substrate.

In the case 2, the display screen is formed only over the firstsubstrate. In the case 3, the display screen is formed only over thesecond substrate.

Moreover, the following three cases 4, 5, and 6 can be thought in thesecond layout method. In the case 4, the first and second substrates arelight transmitting substrates, and an organic light emitting elementprovided over the first substrate and an organic light emitting elementprovided over the second substrate emit light toward both sides of eachsubstrate. In the case 5, the first substrate is a light transmittingsubstrate and an organic light emitting element provided over the firstsubstrate emits light toward the both sides of the first substratewhereas an organic light emitting element provided over the secondsubstrate emits light toward a surface of the second substrate oppositeto the other surface of the second substrate over which the organiclight emitting element is provided, i.e., toward the first substrate. Inthe case 6, the second substrate is a light transmitting substrate andan organic light emitting element provided over the second substrateemits light toward the both sides of the second substrate whereas anorganic light emitting element provided over the first substrate emitslight toward a surface of the first substrate opposite to the othersurface of the first substrate over which the organic light emittingelement is provided, i.e., toward the second substrate.

In the case 4, display screens are formed over the first and secondsubstrates, and an image recognized on the display screen formed overthe first substrate is a mirrored image of an image recognized on thedisplay screen formed over the second substrate. Further, since thefirst and second substrates are the light transmitting substrates, thedisplay screens of the first and second substrates are formed while aviewer can see the view beyond the first and second substrates.

Further, by providing polarizing plates over the first and secondsubstrates, it is possible to prevent a viewer from seeing the viewbeyond the first and second substrates on both of the display screenformed over the first substrate and the display screen formed over thesecond substrate.

In the case 5, the display screen is formed only over the firstsubstrate. In the case 6, the display screen is formed only over thesecond substrate.

In the present invention, as a light transmitting substrate, a quartzsubstrate, a glass substrate, a plastic substrate, or the like is used.When heat treatment at a temperature of 600° C. or more is performed ina process of manufacturing an element such as a thin film transistor oran organic light emitting element over a substrate, a quartz substrateis used. When heat treatment at a temperature of 600° C. or less isperformed, a glass substrate or a plastic substrate may be used. Here,the light transmitting substrate indicates a substrate which transmitsvisible light therethrough. This represents visible light transmittanceof the substrate is 80 to 100%.

In each of the above mentioned cases 2 and 5, the light transmittingsubstrate is used as the first substrate whereas a material of thesecond substrate is not particularly limited and a substrate having nolight transmitting property may be used as the second substrate.

Further, in each of the cases 3 and 6, the light transmitting substrateis used as the second substrate whereas a material of the firstsubstrate is not particularly limited and a substrate having no lighttransmitting property may be used as the first substrate.

In the above described structures of the present invention, an activematrix display device is preferable.

Organic light emitting elements mentioned in this specification includenot only an organic light emitting element having a structure in which afilm sandwiched between a first electrode and a second electrodecontains an organic compound but also an organic light emitting elementhaving a structure in which a film sandwiched between a first electrodeand a second electrode partly contains an inorganic compound in additionto an organic compound.

Organic light emitting materials include a material which can convertenergy upon returning to a ground state from a singlet excited stateinto light emission (a fluorescent material) and a material which canconvert energy upon returning to a ground state from a triplet excitedstate into light emission (a phosphorescent material). Either thefluorescent material or the phosphorescent material may be used as anorganic light emitting material used for a display device of the presentinvention.

As a structure of an organic compound layer, it is possible to employvarious known structures such as a structure formed by laminating a holetransporting layer, a light emitting layer, and an electron transportinglayer in this order, and a structure formed by laminating a holeinjecting layer, a hole transporting layer, a light emitting layer, anelectron transporting layer, and an electron injecting layer in thisorder.

In a display device of the present invention, a method for driving thedisplay device for image display is not particularly limited, and forexample, a dot sequential driving method, a line sequential drivingmethod, a surface sequential driving method, and the like may be used.As a method for expressing a gray scale of an organic light emittingelement, either a digital gray scale method or an analog gray scalemethod may be employed. Further, a source line of the display device maybe input with either analog signals or digital signals. A driver circuitand the like may be arbitrarily designed according to image signals.

By providing a substrate having a white organic light emitting elementin addition to a substrate having red, green, and blue organic lightemitting elements, luminance of only the white organic light emittingelement can be increased so that brightness of only a display screen canbe improved. Since the substrate having the white organic light emittingelement is provided separately from the substrate having the red, green,and blue organic light emitting elements for performing color display,the luminance of the white organic light emitting element can be changedindependently from the red, green, and blue organic light emittingelements. Therefore, brightness of the display screen can be easilycontrolled.

Further, when white color is displayed on a conventional organic ELdisplay which can perform color display, red, green, and blue organiclight emitting elements emit light and three colors of light emittedfrom the organic light emitting elements are mixed to display whilecolor. However, in the structure of the present invention in which asubstrate having red, green, and blue organic light emitting elementsand a substrate having a white organic light emitting element areoverlapped with each other, only the white organic light emittingelement emits light while the red, green, and blue organic lightemitting elements emit no light so as to display white color. Therefore,power consumption can be more reduced as compared to the case ofdisplaying white color by making the red, green, and blue organic lightemitting elements emit light.

When areas of light emitting regions of red and blue organic lightemitting elements are set larger than an area of a light emitting regionof a green organic light emitting element, it is possible to balance thered, green, and blue colors.

In the case where an organic light emitting element which emits lightwith a color by which a range of a triangle of a chromaticity coordinateof red, a chromaticity coordinate of green, and a chromaticitycoordinate of blue can be widened, is provided separately from red,green, and blue organic light emitting elements, colors which cannot beexpressed only by red, green, and blue organic light emitting elements,can be expressed, so that more microscopic and realistic images can bedisplayed.

Furthermore, when red, green, and blue organic light emitting elementsare provided over a first substrate and red, green, and blue organiclight emitting elements are provided over a second substrate and thefirst and second substrates are attached to each other such that thedifferent colored organic light emitting elements provided over thefirst and second substrates are overlapped with one another as seen froma viewer side, image resolution performance can be improved.

Moreover, when a substrate over which red, green, and blue organic lightemitting elements are provided is overlapped with a substrate over whicha blue organic light emitting element is provided, luminance of bluelight emission can be compensated, making it possible to improve balanceof luminance of red, green, and blue.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a display device according to thepresent invention;

FIGS. 2A to 2C are top views showing a pixel structure of a displaydevice described in Embodiment Mode 1;

FIGS. 3A and 3B are cross sectional views showing one pixel of a displaydevice described in Embodiment Mode 1;

FIG. 4 is a view showing a cross sectional structure of one pixel of adisplay device described in Embodiment Mode 1;

FIG. 5 is a view showing a cross sectional structure of one pixel of adisplay device described in Embodiment Mode 1;

FIGS. 6A to 6C are top views showing a pixel structure of a displaydevice described in Embodiment Mode 3;

FIGS. 7A and 7B are cross sectional views showing one pixel of a displaydevice described in Embodiment Mode 3;

FIGS. 8A and 8B are cross sectional views showing one pixel of a displaydevice described in Embodiment Mode 3;

FIGS. 9A to 9C are top views showing a pixel structure of a displaydevice described in Embodiment Mode 3;

FIGS. 10A and 10B are cross sectional views showing one pixel of adisplay device described in Embodiment Mode 3;

FIGS. 11A and 11B are cross sectional views showing one pixel of adisplay device described in Embodiment Mode 3;

FIGS. 12A to 12C are top views showing a pixel structure of a displaydevice described in Embodiment Mode 4;

FIGS. 13A and 13B are cross sectional views showing one pixel of adisplay device described in Embodiment Mode 4;

FIGS. 14A to 14C are top views showing a pixel structure of a displaydevice described in Embodiment Mode 6;

FIG. 15 is a view showing a cross sectional structure of one pixel of adisplay device described in Embodiment Mode 6;

FIG. 16 is a diagram explaining an effect of a display device describedin Embodiment Mode 6;

FIG. 17 is a diagram explaining an effect of a display device describedin Embodiment Mode 6;

FIGS. 18A to 18C are top views showing a pixel structure of a displaydevice described in Embodiment Mode 2;

FIG. 19 is a view showing a cross sectional structure of one pixel of adisplay device described in Embodiment Mode 2;

FIGS. 20A to 20C are top views showing a pixel structure of a displaydevice described in Embodiment 1;

FIGS. 21A and 21B are cross sectional views showing a pixel structure ofa display device described in Embodiment 2;

FIG. 22 is a cross sectional view showing a pixel structure of a displaydevice described in Embodiment 2;

FIG. 23 is a cross sectional view showing a display device described inEmbodiment 3;

FIG. 24 is a cross sectional view showing a display device described inEmbodiment 3;

FIGS. 25A to 25H are diagrams showing electronic appliances described inEmbodiment 4;

FIG. 26 is a diagram showing an electronic appliance described inEmbodiment 4;

FIGS. 27A to 27C are top views showing a pixel structure of a displaydevice described in Embodiment 3;

FIGS. 28A and 28B are cross sectional views showing one pixel of adisplay device described in Embodiment Mode 3;

FIGS. 29A to 29C are top views showing a pixel structure of a displaydevice described in Embodiment Mode 6;

FIG. 30 is a view showing a cross sectional structure of one pixel of adisplay device described in Embodiment Mode 6; and

FIGS. 31A and 31B are cross sectional views of a display devicedescribed in Embodiment 4.

DETAILED DESCRIPTION OF THE INVENTION Embodiment Modes

Embodiment modes of the present invention will be described below.

Embodiment Mode 1

In this embodiment mode, a display device formed by attaching asubstrate having a white (W) organic light emitting element to asubstrate having red (R), green (G), and blue (B) organic light emittingelements, will be described. A perspective view of a display deviceaccording to the present invention is shown in FIG. 1. In FIG. 1,reference numeral 100 is a first substrate over which red (R), green(G), and blue (B) organic light emitting elements are formed; 101, asecond substrate over which a white organic light emitting element isformed; and 102, a display screen. Reference numerals 103 and 104 areFPCs (flexible printed circuits); and 130 and 131, peripheral drivercircuits. Over the first substrate 100, a pixel portion (not shown)including a plurality of organic light emitting elements and theperipheral driver circuit 130 are formed. Over the second substrate 101,a pixel portion (not shown) including a plurality of organic lightemitting elements and the peripheral driver circuit 131 are formed. Thefirst substrate 100 and the second substrate 101 are attached to eachother such that a surface of the first substrate over which the red,green, and blue organic light emitting elements are provided faces asurface of the second substrate over which the white organic lightemitting element is provided, as shown in FIG. 1. Further, the displayscreen 102 is formed over the first substrate 100.

Although a case where the peripheral driver circuits are formed over thefirst and second substrates in FIG. 1, the peripheral driver circuitsmay not be provided thereover. Alternatively, driver circuits may beprovided over ICs and the ICS may be connected to the first and secondsubstrates by using a TAB technology, a COG technology, or the like.

FIGS. 2A to 2C shows pixel structures of a display device of EmbodimentMode 1. FIG. 2A shows a pixel structure as seen from the display screen102 side, that is, from a viewer side. FIG. 2B shows a pixel structureof the first substrate, and FIG. 2C shows a pixel structure of thesecond substrate. Each of FIGS. 2B and 2C is a top view as seen from thesurface provided with the organic light emitting element(s). When thefirst substrate having the pixel structure shown in FIG. 2B isoverlapped with the second substrate having the pixel structure shown inFIG. 2C such that the organic light emitting elements provided over thefirst and second substrates face one another, the pixel structure asshown in FIG. 2A can be obtained as seen from the display screen 102side, i.e., from a viewer side. Note that, a wiring and the like are notshown in FIGS. 2A to 2C so as to simply show the overlapped lightemitting regions.

In FIG. 2B, reference numeral 201 indicates a red light emitting regionincluding a red organic light emitting element; 202, a green lightemitting region including a green organic light emitting element; and203, a blue light emitting region including a blue organic lightemitting element. In FIG. 2C, reference numeral 204 indicates a whitelight emitting region including a white organic light emitting element.

Shaded portions in FIGS. 2A and 2B are light shielding regions since awiring, an element for driving the organic light emitting elements, andthe like are formed over the first substrate. A shaded portion in FIG.2C is a light shielding region since a wiring, an element for drivingthe organic light emitting element, and the like are formed over thesecond substrate. Therefore, when the first and second substrates areoverlapped with each other, light emitted from the white light emittingregion is partly shielded by the light shielding region of the firstsubstrate as seen from the viewer side, as shown in FIG. 2A.

When the red light emitting region 201, the green light emitting region202, and the blue light emitting region 203 provided over the firstsubstrate and the white light emitting region 204 provided over thesecond substrate emit light, a viewer sees three different colored lightemitting regions denoted by reference numerals 205, 206, and 207. Inthis case, a red light emitting region which is lightened by white lightemission, is formed in reference numeral 205. A green light emittingregion which is lightened by white light emission, is formed inreference numeral 206. A blue light emitting region which is lightenedby white light emission, is formed in reference numeral 207.

Further, the color of the light emitting regions over the secondsubstrate is shown in parentheses in reference numerals 205, 206, and207 of FIG. 2A. Specifically, in reference numeral 205, “R” and “(W)”indicate that the red light emitting region over the first substrate isoverlapped with the white light emitting region over the secondsubstrate. In reference numeral 206, “G” and “(W)” indicate that thegreen light emitting region over the first substrate is overlapped withthe white light emitting region over the second substrate. In referencenumeral 207, “B” and “(W)” indicate that the blue light emitting regionover the first substrate is overlapped with the white light emittingregion over the second substrate.

FIGS. 3A and 3B are cross sectional views of the pixel structures shownin FIGS. 2A to 2C. FIG. 3A is a cross sectional view along a line A-A′of FIG. 2A. FIG. 3B is a cross sectional view along a line B-B′ of FIG.2A. The cross sectional views shown in FIGS. 3A and 3B are provided tosimply show positional relations of the organic light emitting elementsprovided over the first substrate to the organic light emitting elementprovided over the second substrate in the display device of the presentinvention. Therefore, only the red, green, and blue organic lightemitting elements provided over the first substrate and the whiteorganic light emitting element provided over the second substrate areshown in FIGS. 3A and 3B. That is, in an actual cross sectionalstructure of the display device, an insulating film and the like areprovided between the substrate and the organic light emitting elementsrather than the structure in which the organic light emitting elementsare provided in contact with the surface of the substrate. However,component parts other than the substrates and the organic light emittingelements are omitted here. This is the same for the cross sections viewsof the following embodiment modes and embodiments. Note that, a specificexample of the cross sectional structures will be described inembodiments below.

In FIG. 3A, a red (R) organic light emitting element 121, a green (G)organic light emitting element 122, and a blue (B) organic lightemitting element 123 are provided over a first substrate 100 whereas awhite organic light emitting element 120 is provided over a secondsubstrate 101. As shown in FIG. 3A, the first substrate 100 and thesecond substrate 101 are overlapped with each other such that the redorganic light emitting element 121, the green organic light emittingelement 122, and the blue organic light emitting element 123 providedover the first substrate face the white organic light emitting element120 provided over the second substrate.

By forming such the structure, the second substrate 101 serves as acounter substrate with respect to the first substrate 100 whereas thefirst substrate 100 serves as a counter substrate with respect to thesecond substrate 101, and the organic light emitting elements can besealed with only the first and second substrates 100 and 101. Therefore,the display device of the present invention can have almost the samethickness as a normal display device in which an organic light emittingelement is provided over a substrate and is sealed with a countersubstrate.

The organic light emitting elements 121, 122, and 123 provided over thefirst substrate 100 have a dual emission structure in which the organiclight emitting elements emit light toward a surface of the firstsubstrate 100 over which the organic light emitting elements areprovided and toward the other surface of the first substrate opposite tothe surface of the first substrate over which the organic light emittingelements are provided. Meanwhile, the white organic light emittingelement 120 provided over the second substrate 101 has a top emissionstructure in which the white organic light emitting element emits lighttoward a surface of the second substrate 101 over which the whiteorganic light emitting element is provided. Further, arrows indicate thedirections of light emitted from the respective organic light emittingelements in FIG. 3A.

By employing such the structure, light generated in the white organiclight emitting element 120 and the red, green, and blue organic lightemitting elements 121, 122, and 123 can be emitted toward the surface ofthe first substrate 100 opposite to the other surface of the firstsubstrate over which the red, green, and blue organic light emittingelements 121, 122, and 123 are provided. That is, a display screen canbe formed over the surface of the first substrate 100 opposite to theother surface of the first substrate 100 over which the red, green, andblue organic light emitting elements 121, 122, and 123 are provided.Accordingly, an image of which brightness is controlled by lightemission of the white organic light emitting element 120, can bedisplayed on the surface of the first substrate 100 opposite to theother surface of the first substrate over which the red, green, and blueorganic light emitting elements 121, 122, and 123 are provided.

The red organic light emitting element 121 includes a first electrode110, a second electrode 108, and a layer 109 containing an organiccompound sandwiched between the first electrode 110 and the secondelectrode 108. The green organic light emitting element 122 includes afirst electrode 113, a second electrode 111, and a layer 112 containingan organic compound sandwiched between the first electrode 113 and thesecond electrode 111. The blue organic light emitting element 123includes a first electrode 116, a second electrode 114, and a layer 115containing an organic compound sandwiched between the first electrode116 and the second electrode 114.

The first electrodes 110, 113, and 116 and the second electrodes 108,111, and 114 of the red, green, and blue organic light emitting elements121, 122, and 123 are respectively formed using a transparent conductivefilm made from indium tin oxide (ITO), and indium zinc oxide (IZO) inwhich indium oxide contains zinc oxide, and the like. The materials usedas the transparent conductive film is not particularly limited to theabove mentioned materials, and a thin metal film and the like can beused in addition to the above materials.

Further, the first electrodes 110, 113, and 116 of the red, green, andblue organic light emitting elements 121, 122, and 123 are formed bypatterning the same transparent conductive film. Also, the secondelectrodes 108, 111, and 114 of the red, green, and blue organic lightemitting elements 121, 122, and 123 are formed by pattering the sametransparent conductive film.

By forming the first and second electrodes of each organic lightemitting element with the transparent conductive films, each organiclight emitting element can be of a dual emission type.

The white organic light emitting element 120 includes a first electrode105, a second electrode 107, and a layer 106 containing an organiccompound sandwiched between the first electrode 105 and the secondelectrode 107.

As the first electrode 105 of the white organic light emitting element120, an electrode having a function of reflecting light is preferablyused. When the first electrode 105 of the white organic light emittingelement 120 has a function of reflecting light, light emitted toward thesecond substrate 101 side from the red, green, and blue organic lightemitting elements 121, 122, and 123 can be reflected by the firstelectrode 105 of the white organic light emitting element 120. Thus,light emitted from the red, green, and blue organic light emittingelements 121, 122, and 123 can be efficiently utilized.

As a material for forming the electrode having a function of reflectinglight, for example, a metal film with high reflectivity such as analuminum film (including an aluminum alloy film and an aluminum filmcontaining an additive) and a silver thin film can be given. The entirefirst electrode 105 is not necessary to have a function of reflectinglight as long as the first electrode 105 can reflect light emitted fromthe organic light emitting elements provided over the first substrate.Further, metal with high reflectivity which is stacked with atransparent conductive film, can be used as the first electrode 105. Inaddition, an electrode at least whose top surface is coated with a metalfilm with high reflectivity, for example, a conductive film whose topsurface (a surface facing the second substrate) is aluminum-plated orsilver-plated, may be used as the first electrode 105.

By using an electrode having a function of reflecting light as the firstelectrode 105 of the white organic light emitting element 120, lightemitted toward the second substrate 101 from the red, green, and blueorganic light emitting elements 121, 122, and 123 can be reflected bythe first electrode 105. Accordingly, the first electrode 105 of thewhite organic light emitting element 120 is preferably provided tooverlap with all of the light emitting regions formed by the red, green,and blue organic light emitting elements 121, 122, and 123. This canefficiently utilize light emitted from the red, green, and blue organiclight emitting elements 121, 122, and 123.

As the second electrode 107 of the white organic light emitting element120, a transparent conductive film made from indium tin oxide (TIO),indium zinc oxide (IZO) in which indium oxide contains zinc oxide, orthe like is used. A material of a transparent conductive film is notlimited to the above mentioned materials, and a metal thin film can alsobe used in addition to these materials.

In the display device of this embodiment mode, a white pixel is placedto overlap with each of a red pixel, a green pixel, and a blue pixel,and therefore, brightness of a display screen can be controlled bychanging luminance of only the white organic light emitting element.

Current-luminance characteristics of the red, green, and blue organiclight emitting elements are different from one another. In aconventional display device, in order to change brightness of only anentire display surface, luminance of each of red, green, and blueorganic light emitting elements must be changed while keeping a balanceof red, green, and blue colors. However, in the display device of thethis embodiment mode, the brightness of only the entire display screencan be changed by changing luminance of only the white organic lightemitting element.

Accordingly, when a light sensor for detecting surrounding brightness isprovided and luminance of the white organic light emitting element ischanged in accordance with the surrounding brightness detected by thelight sensor, brightness of the entire display screen can be changed inaccordance with the surrounding brightness in using the display device.

Further, in the display device of this embodiment mode, since a whitedot is arranged to overlap with red, green, and blue dots, only a whitecolor can be displayed by making only the white organic light emittingelement emit light while making the red, green, and blue organic lightemitting elements emit no light.

In a normal display device performing color display by using red, green,and blue dots as one pixel, a white color is displayed by making thered, green, and blue dots emit light. However, in the display device ofthis embodiment mode, since the white organic light emitting element isformed over the substrate different from the substrate over which thered, green, and blue organic light emitting elements are formed, onepixel can be displayed by making only the white organic light emittingelement emit light. As compared to the case of displaying a white colorby making the red, green, and blue dots emit light, the powerconsumption can be reduced.

Furthermore, in a case where a white organic light emitting element isformed over the same substrate as red, green, and blue organic lightemitting elements, the number of dots formed over one substrate isincreased, which results in reduction of the number of pixels. However,in the structure of this embodiment mode, since the white organic lightemitting element is formed over the substrate different from thesubstrate over which the red, green, and blue organic light emittingelements are formed, both of color display and only white display can beperformed without reducing the number of pixels. Also, when displayingonly the white color, the power consumption can be reduced.

Although an example in which the red, green, and blue organic lightemitting elements being of the dual emission type are formed over thefirst substrate, the white organic light emitting element being of thetop emission type is formed over the second electrode, and the displayscreen is formed over the first substrate, is shown in FIGS. 2A to 2Cand FIG. 3A, the present invention is not limited thereto.

For example, as shown in FIG. 4, the positions of the organic lightemitting elements provided over the first substrate and the organiclight emitting element provided over the second substrate, may becounterchanged.

The same portions as those of FIG. 3A are denoted by the same referencenumerals in FIG. 4. Differing from FIG. 3A, in a structure of FIG. 4,the positions of the organic light emitting elements provided over thefirst substrate 100 and the organic light emitting element provided overthe second substrate 101 are counterchanged.

That is, differing from the structure of FIG. 3A, in FIG. 4, the whiteorganic light emitting element 120 is provided over the first substrate;the red, green, and blue organic light emitting elements 121, 122, and123 are provided over the second substrate; the first electrode 105 andthe second electrode 107 of the white organic light emitting element 120are formed using transparent conductive films; the second electrodes108, 111, and 114 of the red, green, and blue organic light emittingelements 121, 122, and 123 are formed using a transparent conductivefilm; and the first electrodes 110, 113, and 116 of the red, green, andblue organic light emitting elements 121, 122, and 123 are formed byusing electrodes having a function of reflecting light.

When a display screen is provided only over the first substrate, a dualemission type organic light emitting element is provided over the firstsubstrate 100, and a top emission type organic light emitting element isprovided over the second substrate 101. Therefore, in the structure asshown in FIG. 4, the white organic light emitting element 120 formedover the first substrate is of a dual emission type and the red, green,and blue organic light emitting elements 121, 122, and 123 formed overthe second substrate are of a top emission type. Note that, in FIG. 4,arrows indicate directions of light emitted from the respective organiclight emitting elements.

Although the case of providing the display screen only over the firstsubstrate is shown in FIG. 3A and FIG. 4, display screens may be formedover both of the first and second substrates.

FIG. 5 shows a structural example in which display screens are formedover both of the first and second substrates. The same portions as thoseof FIG. 3A are also denoted by the same reference numerals in FIG. 5.

Differing from FIG. 3A, the first electrode 105 of the white organiclight emitting element 120 provided over the second substrate 101 isformed using a transparent conductive film in FIG. 5. As shown in FIG.5, arrows indicate the directions of light emitted from the respectiveorganic light emitting elements.

Since all the first electrodes and the second electrodes of the red,green, and blue organic light emitting elements 121, 122, and 123provided over the first substrate and the white organic light emittingelement 120 provided over the second substrate are formed usingtransparent conductive films, the red, green, and blue organic lightemitting elements 121, 122, and 123 provided over the first substrateand the white organic light emitting element 120 provided over thesecond substrate are the dual emission type organic light emittingelements. Accordingly, light can be emitted through both of the firstand second substrates 100 and 101 as shown in FIG. 5, and hence, displayscreens can be formed over both of the first and second substrates.

An image recognized on the display screen formed over the firstsubstrate is a mirrored image of an image recognized on the displayscreen formed over the second substrate. Further, since the first andsecond substrates are the light transmitting substrates, the displayscreens are formed such that a viewer can see the view beyond the firstand second substrates.

Note that, by providing polarizing plates over the first and secondsubstrates, it is possible to prevent a viewer from seeing the viewbeyond the first and second substrates on the display screens formedover the first and second substrates.

Embodiment Mode 2

In this embodiment mode, an example according to the case B of the firststructure of the present invention will be described. Specifically, acase in which a dot of a white organic light emitting element isprovided over a second substrate so as to face a dot of a red organiclight emitting element provided over a first substrate, a dot of a whiteorganic light emitting element is provided over the second substrate soas to face a dot of a green organic light emitting element provided overthe first substrate, and a dot of a white organic light emitting elementis provided over the second substrate so as to face a dot of a blueorganic light emitting element provided over the first substrate, willbe described. Note that, a case of forming a display screen over thefirst substrate (that is, an image is displayed on the first substrateside) will be described in this embodiment mode.

FIGS. 18A to 18C show pixel structures of a display device according tothis embodiment mode. FIG. 18A shows a pixel structure as seen from thedisplay screen side, that is, from a viewer side. FIG. 18B shows a pixelstructure of the first substrate, and FIG. 18C shows a pixel structureof the second substrate. Each of FIGS. 18B and 18C is a top view as seenfrom the surface provided with the organic light emitting elements. Whenthe first substrate having the pixel structure shown in FIG. 18B isoverlapped with the second substrate having the pixel structure shown inFIG. 18C such that the surfaces provided with the organic light emittingelements of the first and second substrates face one another, the pixelstructure as shown in FIG. 18A can be obtained as seen from the displayscreen 102 side, i.e., from a viewer side. Note that, a wiring and thelike are not shown in FIGS. 18A to 18C so as to simply show theoverlapped light emitting regions.

In FIG. 18B, reference numeral 1200 indicates a red light emittingregion including a red organic light emitting element; 1201, a greenlight emitting region including a green organic light emitting element;and 1202, a blue light emitting region including a blue organic lightemitting element. In FIG. 18C, each of reference numerals 1203, 1204,and 1205 indicates a white light emitting regions including a whiteorganic light emitting element.

Shaded portions in FIGS. 18A and 18B are light shielding regions since awiring, an element for driving the organic light emitting elements, andthe like are formed over the first substrate. A shaded portion in FIG.18C is a light shielding region since a wiring, an element for drivingthe organic light emitting element, and the like are formed over thesecond substrate. In this embodiment mode, the light emitting regionsformed over the first substrate has almost the same size as the lightemitting regions formed over the second substrate, and both of the lightemitting regions are arranged to overlap with each other at the samepositions. Accordingly, the light shielding region of the firstsubstrate is formed at almost the same position as the light shieldingregion of the second substrate.

When the red, green, and blue light emitting regions 1200, 1201, and1202 provided over the first substrate and the white light emittingregions 1203, 1204, and 1205 provided over the second substrate emitlight, a viewer sees three different colored light emitting regionsdenoted by reference numerals 1206, 1207, and 1208. In this case,reference numeral 1206 is a red light emitting region which is lightenedby white light emission. Reference numeral 1207 is a green lightemitting region which is lightened by white light emission. Referencenumeral 1208 is a blue light emitting region which is lightened by whitelight emission.

Further, the colors of the light emitting regions over the secondsubstrate are shown in parentheses since the light emitting regions overthe first substrate are overlapped with the light emitting regions overthe second substrate in reference numerals 1206, 1207, and 1208 in FIG.18A. Specifically, in reference numeral 1206, “R” and “(W)” indicatethat the red light emitting region over the first substrate isoverlapped with the white light emitting region over the secondsubstrate. In reference numeral 1207, “G” and “(W)” indicate that thegreen light emitting region over the first substrate is overlapped withthe white light emitting region over the second substrate. In referencenumeral 1208, “B” and “(W)” indicate that the blue light emitting regionover the first substrate is overlapped with the white light emittingregion over the second substrate.

In the case of making only the red light emitting region 1200 over thefirst substrate emit light, reference numeral 1206 becomes a red lightemitting region, whereas in the case of making only the white lightemitting region 1203 over the second substrate emit light, referencenumeral 1206 becomes a white light emitting region. In the case ofmaking only the green light emitting region 1201 over the firstsubstrate emit light, reference numeral 1207 becomes a green lightemitting region, whereas in the case of making only the white lightemitting region 1204 over the second substrate emit light, referencenumeral 1207 becomes a white light emitting region. In the case ofmaking only the blue light emitting region 1202 over the first substrateemit light, reference numeral 1208 becomes a blue light emitting region,whereas in the case of making only the white light emitting region 1205over the second substrate emit light, reference numeral 1208 becomes awhite light emitting region.

FIG. 19 is a cross sectional view along a line A-A′ of FIG. 18A. FIG. 19is a schematic cross sectional view to simply show a cross sectionalstructure of a display device according to the present invention. Onlyred, green, and blue organic light emitting elements provided over afirst substrate and white organic light emitting elements provided overa second substrate, are shown.

In FIG. 19, a red (R) organic light emitting element 1311, a green (G)organic light emitting element 1312, and a blue (B) organic lightemitting element 1313 are provided over a first substrate 1300 whereaswhite organic light emitting elements 1323, 1324, and 1325 are providedover a second substrate 1301. As shown in FIG. 19, the first substrate1300 and the second substrate 1301 are attached to each other such thatthe red organic light emitting element 1311 provided over the firstsubstrate faces the white organic light emitting element 1323 providedover the second substrate, the green organic light emitting element 1312provided over the first substrate faces the white organic light emittingelement 1324 provided over the second substrate, and the blue organiclight emitting element 1313 provided over the first substrate faces thewhite organic light emitting element 1325 provided over the secondsubstrate.

By forming such the structure, the second substrate 1301 serves as acounter substrate with respect to the first substrate 1300 whereas thefirst substrate 1300 serves as a counter substrate with respect to thesecond substrate 1301, and the organic light emitting elements can besealed with only the first and second substrates 1300 and 1301.Therefore, the display device of the present invention can have almostthe same thickness as a normal display device in which an organic lightemitting element is provided over one substrate and sealed with acounter substrate.

The organic light emitting elements 1311, 1312, and 1313 provided overthe first substrate 1300 have a dual emission structure in which theorganic light emitting elements 1311, 1312, and 1313 emit light toward asurface of the first substrate over which the organic light emittingelements 1311, 1312, and 1313 are provided and toward the other surfaceof the first substrate opposite to the surface of the first substrateover which the organic light emitting elements are provided. Meanwhile,the white organic light emitting elements 1323, 1324, and 1325 providedover the second substrate 1301 has a top emission structure in which thewhite organic light emitting elements 1323, 1324, and 1325 emit lighttoward a surface of the second substrate over which the white organiclight emitting elements are provided. Further, arrows indicate thedirections of light emitted from the respective organic light emittingelements in FIG. 19.

By employing such the structure, light generated in the white organiclight emitting elements 1323, 1324, and 1325 and the red, green, andblue organic light emitting elements 1311, 1312, and 1313 can be emittedtoward the surface of the first substrate 1300 opposite to the othersurface of the first substrate over which the red, green, and blueorganic light emitting elements 1311, 1312, and 1313 are provided. Thatis, a display screen can be formed over the surface of the firstsubstrate 1300 opposite to the other surface of the first substrate 1300over which the red, green, and blue organic light emitting elements1311, 1312, and 1313 are provided.

The red organic light emitting element 1311 includes a first electrode1302, a second electrode 1304, and a layer 1303 containing an organiccompound sandwiched between the first electrode 1302 and the secondelectrode 1304. The green organic light emitting element 1312 includes afirst electrode 1305, a second electrode 1307, and a layer 1306containing an organic compound sandwiched between the first electrode1305 and the second electrode 1307. The blue organic light emittingelement 1313 includes a first electrode 1308, a second electrode 1310,and a layer 1309 containing an organic compound sandwiched between thefirst electrode 1308 and the second electrode 1310.

The first electrodes 1302, 1305, and 1308 and the second electrodes1304, 1307, and 1310 of the red, green, and blue organic light emittingelements 1311, 1312, and 1313 are formed using transparent conductivefilms made from indium tin oxide (ITO), indium zinc oxide (IZO) in whichindium oxide contains zinc oxide, and the like. The materials used asthe transparent conductive films are not particularly limited to theabove mentioned materials, and a thin metal film and the like can beused in addition to the above materials.

Further, the first electrode 1302 of the red organic light emittingelement 1311, the first electrode 1305 of the green organic lightemitting element 1312, and the first electrode 1308 of the blue organiclight emitting element 1313 are formed by patterning the sametransparent conductive film. Also, the second electrode 1304 of the redorganic light emitting element 1311, the second electrode 1307 of thegreen organic light emitting element 1312, and the second electrode 1310of the blue organic light emitting element 1313 are formed by patteringthe same transparent conductive film.

By forming the first and second electrodes of each organic lightemitting element with the transparent conductive films, each organiclight emitting element can be of a dual emission type.

The white organic light emitting element 1323 includes a first electrode1314, a second electrode 1316, and a layer 1315 containing an organiccompound sandwiched between the first electrode 1314 and the secondelectrode 1316. The white organic light emitting element 1324 includes afirst electrode 1317, a second electrode 1319, and a layer 1318containing an organic compound sandwiched between the first electrode1317 and the second electrode 1319. The white organic light emittingelement 1325 includes a first electrode 1320, a second electrode 1322,and a layer 1321 containing an organic compound sandwiched between thefirst electrode 1320 and the second electrode 1321.

As the first electrodes 1314, 1317, and 1320 of the white organic lightemitting elements 1323, 1324, and 1325, electrodes having a function ofreflecting light are preferably used. When the first electrodes 1314,1317, and 1320 of the white organic light emitting elements 1323, 1324,and 1325 have a function of reflecting light, light emitted toward thesecond substrate 1301 from the red, green, and blue organic lightemitting elements 1311, 1312, and 1313 can be reflected by the firstelectrodes 1314, 1317, and 1320 of the white organic light emittingelements 1323, 1324, and 1325. Thus, light generated in the red, green,and blue organic light emitting elements 1311, 1312, and 1313 can beefficiently utilized.

In the structure shown in this embodiment mode, luminance of white lightemission overlapped with red, green, or blue light emission can beindividually controlled. That is, brightness of red, green, and blue canbe individually controlled in each pixel. Therefore, for example, whenluminance of light emitted from a white light emitting region positionedto be overlapped with a red light emitting region as seen from a viewerside, is increased, that is, when the luminance of only the whiteorganic light emitting element provide to face the red organic lightemitting element is increased, brightness of only red emission can beincreased so that a pink color can be displayed.

Further, in the case where a dot of a white organic light emittingelement is provided over the second substrate so as to face a dot of ared organic light emitting element provided over a first substrate, adot of another white organic light emitting element is provided over thesecond substrate so as to face a dot of a green organic light emittingelement provided over the first substrate, and a dot of another whiteorganic light emitting element is provided over the second substrate soas to face a dot of a blue organic light emitting element provided overthe first substrate, when all of the white organic light emittingelements provided to face each of the red, green, and blue organic lightemitting elements has the same luminance, brightness of an entiredisplay screen can be controlled as well as Embodiment Mode 1.

In the display device of this embodiment mode, since white dots arearranged to be overlapped with red, green, and blue dots, only a whitecolor can be displayed by making only the white organic light emittingelements emit light while making the red, green, and blue organic lightemitting elements emit no light.

In the display device of this embodiment mode, in order to display onlya white color, one pixel includes one white dot. Accordingly, since thewhite dots are provided to overlap with the red, green, and blue dotsrespectively, when display is performed by only the white dots, thenumber of pixels is three times as high as a case of performing colordisplay, and therefore, high resolution images can be displayed.

In addition, when performing only white display, the number of pixels isthree times as high as Embodiment Mode 1, and therefore, high resolutionimages can be displayed. As a consequence, the structure of EmbodimentMode 2 is more preferable than that of Embodiment Mode 1.

In a normal display device performing color display by using red, green,and blue dots as one pixel, a white color is displayed by making thered, green, and blue dots emit light. However, in the display device ofthis embodiment mode, since the white organic light emitting elementsare formed over the substrate different from the substrate over whichthe red, green, and blue organic light emitting elements are formed, onepixel can be displayed by making only the white organic light emittingelement emit light. As compared to the case of displaying a white colorby making the red, green, and blue dots emit light, the powerconsumption can be reduced.

Furthermore, in the case where white organic light emitting elements areformed over the same substrate as red, green, and blue organic lightemitting elements, the number of dots formed over one substrate isincreased, which results in reduction of the number of pixels. However,in the structure of this embodiment mode, since the white organic lightemitting elements are formed over the substrate different from thesubstrate over which the red, green, and blue organic light emittingelements are formed, both of color display and only white display can beperformed without reducing the number of pixels. Also, when displayingonly the white color, the power consumption can be reduced.

Although an example in which the red, green, and blue organic lightemitting elements are formed over the first substrate, the white organiclight emitting elements are formed over the second substrate, and thedisplay screen is formed over the first substrate, is shown in thisembodiment mode, the present invention is not limited thereto.

For example, the positions of the organic light emitting elementsprovided over the first substrate and the organic light emittingelements provided over the second substrate, may be counterchanged.Specifically, the white organic light emitting elements may be providedover the first substrate whereas the red, green, and blue organic lightemitting elements may be provided over the second substrate.

Further, display screens may be provided over both of the first andsecond substrates. In this case, dual emission type organic lightemitting elements may be provided over both of the first and secondsubstrates. Specifically, first electrodes and second electrodes of theorganic light emitting elements provided over both of the first andsecond substrates may be formed using transparent conductive films.

Embodiment Mode 3

In the first structure of the present invention, a case where red andgreen organic light emitting elements are provided over a firstsubstrate and blue and white organic light emitting elements areprovided over a second substrate, will be described in this embodimentmode.

FIGS. 27A to 27C show pixel structures of a display device according tothis embodiment mode. FIG. 27A shows a pixel structure as seen from adisplay screen side, that is, from a viewer side. FIG. 27B shows a pixelstructure of the first substrate, and FIG. 27C shows a pixel structureof the second substrate. Each of FIGS. 27B and 27C is a top view as seenfrom the surface provided with the organic light emitting elements. Whenthe first substrate having the pixel structure shown in FIG. 27B isoverlapped with the second substrate having the pixel structure shown inFIG. 27C such that the organic light emitting elements provided over thefirst and second substrates face one another, the pixel structure asshown in FIG. 27A can be obtained as seen from the display screen 102side, i.e., from a viewer side. Note that, a wiring and the like are notshown in FIGS. 27A to 27C so as to simply show the overlapped lightemitting regions.

In FIG. 27B, reference numeral 3000 indicates a green light emittingregion including a green organic light emitting element; and 3001, a redlight emitting region including a red organic light emitting element. InFIG. 27C, reference numeral 3002 indicates a blue light emitting regionincluding a blue organic light emitting element; and 3003, a white lightemitting region including a white organic light emitting element.

Shaded portions in FIGS. 27A and 27B are light shielding regions since awiring, an element for driving the organic light emitting elements, andthe like are formed over the first substrate. A shaded portion in FIG.27C is also a light shielding region since a wiring, an element fordriving the organic light emitting elements, and the like are formedover the second substrate. In this embodiment mode, the light emittingregions formed over the first substrate has almost the same size as thelight emitting regions provided over the second substrate, and theselight emitting regions are arranged to overlap with one another at thesame positions. Accordingly, the light shielding region of the firstsubstrate is formed at almost the same position as the light shieldingregion of the second substrate.

When the green light emitting region 3000 and the red light emittingregion 3001 provided over the first substrate, and the blue lightemitting region 3002 and the white light emitting region 3003 providedover the second substrate emit light, a viewer sees two differentcolored light emitting regions denoted by reference numerals 3004 and3005. In this case, a mixed colored light emitting region in which blueand green are mixed, is formed in reference numeral 3004. A red lightemitting region which is lightened by white light emission, is formed inreference numeral 3005.

Note that, the colors of the light emitting regions over the secondsubstrate are shown in parentheses of FIG. 27A since the light emittingregions formed over the first substrate are overlapped with the lightemitting regions formed over the second substrate at the same positions.That is, in reference numeral 3004, “G” and “(B)” indicate that thegreen light emitting region over the first substrate is overlapped withthe blue light emitting region over the second substrate. In referencenumeral 3005, “R” and “(W)” indicate that the red light emitting regionover the first substrate is overlapped with the white light emittingregion over the second substrate.

In the case of making only the green light emitting region 3000 over thefirst substrate emit light, reference numeral 3004 becomes a green lightemitting region, whereas in the case of making only the blue lightemitting region 3002 over the second substrate emit light, referencenumeral 3004 becomes a blue light emitting region. In the case of makingonly the red light emitting region 3001 over the first substrate emitlight, reference numeral 3005 becomes a red light emitting region,whereas in the case of making only the white light emitting region 3003over the second substrate emit light, reference numeral 3005 becomes awhite light emitting region.

Cross sectional views of the pixel structures shown in FIGS. 27A to 27Care shown in FIGS. 28A and 28B. FIG. 28A is a cross sectional view alonga line A-A′ of FIG. 27A, and FIG. 28B is a cross sectional view along aline B-B′ of FIG. 27A. The cross sectional views shown in FIGS. 28A and28B are provided to simply show positional relations of the organiclight emitting elements provided over the first and second substrates inthe display device of the present invention. Therefore, only the red andgreen organic light emitting elements provided over the first substrateand the blue and white organic light emitting elements provided over thesecond substrate are shown in FIGS. 28A and 28B.

In FIG. 28A, a green (G) organic light emitting element 408 and a red(R) organic light emitting element 409 are provided over a firstsubstrate 400 whereas a blue (B) organic light emitting element 416 anda white (W) organic light emitting element 417 are provided over asecond substrate 401. As shown in FIG. 28A, the first substrate 400 andthe second substrate 401 are attached to each other such that the greenorganic light emitting element 408 provided over the first substratefaces the blue organic light emitting element 416 provided over thesecond substrate whereas the red organic light emitting element 409provided over the first substrate faces the white organic light emittingelement 417 provided over the second substrate.

By forming such the structure, the second substrate 401 serves as acounter substrate with respect to the first substrate 400 whereas thefirst substrate 400 serves as a counter substrate with respect to thesecond substrate 401, and the organic light emitting elements can besealed with only the first and second substrates 400 and 401. Therefore,the display device of the present invention can have almost the samethickness as a normal display device in which an organic light emittingelement is formed over only one substrate and sealed with a countersubstrate.

The organic light emitting elements 408 and 409 provided over the firstsubstrate 400 have a dual emission structure in which the organic lightemitting elements emit light toward a surface of the first substrate 400over which the organic light emitting elements 408 and 409 are providedand toward the other surface of the first substrate 400 opposite to thesurface over which the organic light emitting elements are provided,i.e., toward the second substrate 401. Meanwhile, the organic lightemitting elements 416 and 417 provided over the second substrate 401have a top emission structure in which the organic light emittingelements 416 and 417 emit light toward a surface of the second substrate401 over which the organic light emitting elements 416 and 417 areprovided, i.e., toward the first substrate 400. Further, arrows indicatethe directions of light emitted from the respective organic lightemitting elements in FIGS. 28A and 28B.

The green organic light emitting element 408 includes a first electrode402, a second electrode 404, and a layer 403 containing an organiccompound sandwiched between the first electrode 402 and the secondelectrode 404. The red organic light emitting element 409 includes afirst electrode 405, a second electrode 407, and a layer 406 containingan organic compound sandwiched between the first electrode 405 and thesecond electrode 407. The blue organic light emitting element 416includes a first electrode 410, a second electrode 412, and a layer 411containing an organic compound sandwiched between the first electrode410 and the second electrode 412. The white organic light emittingelement 417 includes a first electrode 413, a second electrode 415, anda layer 414 containing an organic compound sandwiched between the firstelectrode 413 and the second electrode 415.

The first electrodes 402 and 405 and the second electrodes 404 and 407of the green and red organic light emitting elements 408 and 409, thesecond electrodes 412 and 415 of the blue and white organic lightemitting elements 416 and 417 are respectively formed using transparentconductive films made from indium tin oxide (ITO), indium zinc oxide(IZO) in which indium oxide contains zinc oxide, and the like. Further,the first electrode 402 of the green organic light emitting element 408and the first electrode 405 of the red organic light emitting element409 are formed by patterning the same transparent conductive film. Thesecond electrode 404 of the green organic light emitting element 408 andthe second electrode 407 of the red organic light emitting element 409are formed by pattering the same transparent conductive film. Also, thesecond electrode 412 of the blue organic light emitting element 416 andthe second electrode 415 of the white organic light emitting element 417are formed by pattering the same transparent conductive film.

By forming the first and second electrodes for each organic lightemitting element provided over the first substrate 400 with thetransparent conductive films, each organic light emitting element can beof a dual emission type.

As the first electrodes 410 and 413 of the blue and white organic lightemitting elements 416 and 417, electrodes having a function ofreflecting light are preferably used. When the first electrodes 410 and413 of the blue and white organic light emitting elements 416 and 417have a function of reflecting light, light emitted toward the secondsubstrate 401 from the green and red organic light emitting elements 408and 409 can be reflected by the first electrodes 410 and 413 of the blueand white organic light emitting elements 416 and 417. Thus, lightemitted from the green and red organic light emitting elements 408 and409 can be efficiently utilized.

Further, in FIGS. 27A to 27C and FIGS. 28A and 28B, all of the lightemitting regions of the organic light emitting elements have the samearea; however, the light emitting regions of the organic light emittingelements may have different areas from one another depending on theircolors.

FIGS. 6A to 6C shows pixel structures of a display device in the casewhere areas of light emitting regions of organic light emitting elementsare different from one another depending on colors. FIG. 6A shows apixel structure as seen from the display screen side, that is, from aviewer side. FIG. 6B shows a pixel structure of a first substrate, andFIG. 6C shows a pixel structure of a second substrate. When the firstsubstrate having the pixel structure shown in FIG. 6B is overlapped withthe second substrate having the pixel structure shown in FIG. 6C suchthat the organic light emitting elements provided over the first andsecond substrates face one another, the pixel structure as shown in FIG.6A can be obtained as seen from a display screen side, i.e., from aviewer side. Each of FIGS. 6B and 6C is a top view as seen from thesurface provided with the organic light emitting elements.

In FIG. 6B, reference numeral 300 indicates a green light emittingregion including a green organic light emitting element; and 301, a redlight emitting region including a red organic light emitting element. InFIG. 6C, reference numeral 302 indicates a blue light emitting regionincluding a blue organic light emitting element; and 303, a white lightemitting region including a white organic light emitting element. Notethat, a wiring and the like are not shown in FIGS. 6A to 6C so as tosimply show the overlapped light emitting regions.

Differing from the structures shown in FIGS. 27A and 27B, areas of lightemitting regions of the red and blue organic light emitting elements arelarger than areas of light emitting regions of the green and whiteorganic light emitting elements. In the example shown in FIGS. 6A to 6C,since the areas of the light emitting regions of the red and blueorganic light emitting elements are larger than the areas of the lightemitting regions of the green and white organic light emitting elements,a part of the light emitting region 301 of the red organic lightemitting element is overlapped with a part of the light emitting region302 of the blue organic light emitting element as seem from a viewerside.

Shaded portions in FIGS. 6A and 6B are light shielding regions since awiring, an element for driving the organic light emitting elements, andthe like are formed over the first substrate. A shaded portion in FIG.6C is also a light shielding region since a wiring, an element fordriving the organic light emitting elements, and the like are formedover the second substrate. Therefore, when the first substrateoverlapped with the second substrate is seen from the first substrateside (a viewer side), light emitted from the organic light emittingelements formed over the second substrate is shielded in a region otherthan the green light emitting region 300 and the red light emittingregion 301 provided over the first substrate. Thus, when a viewer seesthe superimposed first and second substrates from the first substrateside, light emitted from the blue light emitting region 302 providedover the second substrate is partly shielded by the light shieldingregion of the first substrate.

When the green light emitting region 300 and the red light emittingregion 301 provided over the first substrate, and the blue lightemitting region 302 and the white light emitting region 303 providedover the second substrate emit light, a viewer sees four differentcolored light emitting regions denoted by reference numerals 304, 305,306, and 307. In this case, a mixed colored light emitting region inwhich blue and green are mixed, is formed in reference numeral 304. Amixed colored light emitting region in which red and blue are mixed, isformed in reference numeral 305. A red light emitting region is formedin reference numeral 306. A mixed colored light emitting region in whichred and white are mixed, is formed in reference numeral 307.

Further, the colors of the light emitting regions over the secondsubstrate are shown in parentheses in reference numerals 304, 305, 306,and 307 of FIG. 6A. Specifically, in reference numeral 304, “G” and“(B)” indicate that the green light emitting region over the firstsubstrate is overlapped with the blue light emitting region over thesecond substrate. In reference numeral 305, “R” and “(B)” indicate thatthe red light emitting region over the first substrate is overlappedwith the blue light emitting region over the second substrate. Inreference numeral 306, “R” indicates that there is only a part of thered light emitting region provided over the first substrate. Inreference numeral 307, “R” and “(W)” indicate that the red lightemitting region over the first substrate is overlapped with the whitelight emitting region over the second substrate.

In the case of making only the green light emitting region 300 over thefirst substrate emit light, reference numeral 304 becomes a green lightemitting region, whereas in the case of making only the red lightemitting region 301 over the first substrate emit light, referencenumerals 305, 306, and 307 become red light emitting regions. In thecase of making only the blue light emitting region 302 over the secondsubstrate emit light, reference numerals 304 and 305 become blue lightemitting regions, whereas in the case of making only the white lightemitting region 303 over the second substrate emit light, referencenumeral 307 becomes a white light emitting region.

Cross sectional views of the pixel structures shown in FIGS. 6A to 6Care shown in FIGS. 7A and 7B and FIGS. 8A and 8B. FIG. 7A is a crosssectional view along a line A-A′ of FIG. 6A, and FIG. 7B is a crosssectional view along a line B-B′ of FIG. 6A. FIG. 8A is a crosssectional view along a line C-C′ of FIG. 6A, and FIG. 8B is a crosssectional view along a line D-D′ of FIG. 6A. FIGS. 7A and 7B and FIGS.8A and 8B are schematic cross sectional views simply showing crosssectional structures of a display device according to the presentinvention, and each of the drawings shows only a first substrate, greenand red organic light emitting elements provided over the firstsubstrate, a second substrate, and blue and white organic light emittingelements provided over the second substrate. In FIGS. 7A and 7B andFIGS. 8A and 8B, the same portions as those of FIGS. 28A and 28B aredenoted by the same reference numerals.

In FIG. 7A, a green (G) organic light emitting element 408, and a red(R) organic light emitting element 409 are provided over a firstsubstrate 400 whereas a blue (B) organic light emitting element 416 anda white (W) organic light emitting element 417 are provided over asecond substrate 401. As shown in FIG. 7A, the first substrate 400 andthe second substrate 401 are attached to each other such that the greenorganic light emitting element 408 provided over the first substrate 400faces the blue organic light emitting element 416 provided over thesecond substrate 401 whereas the red organic light emitting element 409provided over the first substrate faces a part of the blue organic lightemitting element 416 and the white organic light emitting element 417provided over the second substrate. Note that arrows indicate directionsof light emitted from the respective organic light emitting elements.

Since the visibility of red and blue is lower than that of green, andtherefore, when areas of light emitting regions of the red and blueorganic light emitting elements are set larger than an area of a lightemitting region of the green organic light emitting element, it ispossible to balance the red, green, and blue colors. In addition, sincethe white organic light emitting element is also provided over thesecond substrate, brightness of a display screen can be controlled.Moreover, since two colored organic light emitting elements are providedover each of the first and second substrates, as compared to a case ofproviding three colored organic light emitting elements over asubstrate, wherein the number of pixels provided over the substrate isthe same as the number of pixels provided over the first and secondsubstrates, the number of elements required for driving the organiclight emitting elements provided for each dot can be reduced. As aconsequence, aperture ratio can be improved.

The cross sectional structures along the lines B-B′, C-C′, and D-D′ ofFIG. 6A will hereinafter be described. As shown in FIG. 7B, it is knownthat the green organic light emitting element 408 provided over thefirst substrate 400 faces the blue organic light emitting element 416provided over the second substrate 401 in the line B-B′ of FIG. 6A.

As shown in FIG. 8A, it is known that the red organic light emittingelement 409 provided over the first substrate 400 faces the blue organiclight emitting element 416 provided over the second substrate 401 in theline C-C′ of FIG. 6A.

As shown in FIG. 8B, it is known that the red organic light emittingelement 409 provided over the first substrate 400 faces the whiteorganic light emitting element 417 provided over the second substrate401 in the line D-D′ of FIG. 6A.

The case in which the red and green organic light emitting elements areprovided over the first substrate whereas the blue and white organiclight emitting elements are provided over the second substrate, isdescribed in this embodiment mode; however, the present invention is notlimited thereto. The area of the light emitting regions of the red andblue organic light emitting elements having lower visibility than thegreen, can be set larger than the area of the light emitting region ofthe green organic light emitting element so as to balance the red,green, and blue colors. Therefore, either the red organic light emittingelement or the blue organic light emitting element may be provided overthe same substrate as the green organic light emitting element. Also,the positions of the green and white organic light emitting elements maybe counterchanged. That is, the red and white organic light emittingelements may be provided over the first substrate whereas the blue andgreen organic light emitting elements may be provided over the secondsubstrate.

Note that the respective organic light emitting elements are arrangedsuch that the green organic light emitting element 408 provided over thefirst substrate 400 faces a part of the blue organic light emittingelement 416 provided over the second substrate 401, and the red organiclight emitting element 409 provided over the first substrate faces apart of the blue organic light emitting element and the white organiclight emitting element 417 provided over the second substrate in FIGS.6A to 6C, FIGS. 7A and 7B, and FIGS. 8A and 8B; however, the presentinvention is not limited to this arrangement. For example, the greenorganic light emitting element may face the white organic light emittingelement whereas the red organic light emitting element may face the blueorganic light emitting element. Further, for example, the organic lightemitting elements provided over the second substrate can be provided tobe rotated ±90 degrees.

An example of rotating the organic light emitting elements provided overthe second substrate by +90 degrees will be described with reference toFIGS. 9A to 9C, FIGS. 10A and 10B, and FIGS. 11A and 11B. Pixelstructures in which the organic light emitting elements provided overthe second substrate are rotated by +90 degrees, are shown in FIGS. 9Ato 9C. FIG. 9A shows the pixel structure as seen from a display screenside, i.e., from a viewer side. FIG. 9B shows the pixel structure overthe first substrate, and FIG. 9C shows the pixel structure over thesecond substrate. By overlapping the first substrate having the pixelstructure shown in FIG. 9B with the second substrate having the pixelstructure shown in FIG. 9C such that the organic light emitting elementsprovided over the first substrate face the organic light emittingelements provided over the second substrate, the pixel structure asshown in FIG. 9A is obtained as seen from a display screen side, i.e.,from a viewer side. FIGS. 9B and 9C are top views as seen from eachsurface over which the organic light emitting elements are formed.

In FIG. 9B, reference numeral 500 indicates a green light emittingregion including a green organic light emitting element; and 501, a redlight emitting region including a red organic light emitting element.

In FIG. 9C, reference numeral 502 indicates a blue light emitting regionincluding a blue organic light emitting element; and 503, a white lightemitting region including a white organic light emitting element. Notethat a wiring and the like are not shown in FIGS. 9A to 9C so as tosimply show the overlapped light emitting regions.

Shaded portions in FIGS. 9A and 9B are light shielding regions since awiring, an element for driving the organic light emitting elements, andthe like are formed over the first substrate. A shaded portion in FIG.9C is a light shielding region since a wiring, an element for drivingthe organic light emitting element, and the like are formed over thesecond substrate. Therefore, when a viewer sees the first substrateoverlapped with the second substrate from the first substrate side,light emitted from the organic light emitting elements formed over thesecond substrate is shielded in a region other than the green lightemitting region 500 and the red light emitting region 501 provided overthe first substrate. Thus, when a viewer sees the superimposed first andsecond substrates, light emitted from the blue and white light emittingregions 502 and 503 provided over the second substrate is partlyshielded by the light shielding region of the first substrate.

When the green light emitting region 500 and the red light emittingregion 501 provided over the first substrate, and the blue lightemitting region 502 and the white light emitting region 503 providedover the second substrate emit light, a viewer sees six differentcolored light emitting regions denoted by reference numerals 504, 505,506, 507, 508, and 509. In this case, a mixed colored light emittingregion in which green and blue are mixed, is formed in reference numeral504. A green light emitting region is formed in reference numeral 505. Amixed colored light emitting region in which green and white are mixed,is formed in reference numeral 506. A mixed colored light emittingregion in which red and blue are mixed, is formed in reference numeral507. A red light emitting region is formed in reference numeral 508. Amixed colored light emitting region in which red and white are mixed, isformed in reference numeral 509.

Further, the colors of the light emitting regions over the secondsubstrate are shown in parentheses in reference numerals 504, 506, 507,and 509 of FIG. 9A. Specifically, in reference numeral 504, “G” and“(B)” indicate that the green light emitting region over the firstsubstrate is overlapped with the blue light emitting region over thesecond substrate. In reference numeral 505, “G” indicates that there isonly a part of the green light emitting region provided over the firstsubstrate. In reference numeral 506, “G” and “(W)” indicate that thegreen light emitting region over the first substrate is overlapped withthe white light emitting region over the second substrate. In referencenumeral 507, “R” and “(B)” indicate that the red light emitting regionover the first substrate is overlapped with the blue light emittingregion over the second substrate. In reference numeral 508, “R”indicates that there is only a part of the red light emitting regionprovided over the first substrate. In reference numeral 509, “R” and“(W)” indicate that the red light emitting region over the firstsubstrate is overlapped with the white light emitting region over thesecond substrate.

In the case of making only the green light emitting region 500 over thefirst substrate emit light, reference numerals 504, 505, and 506 becomegreen light emitting regions, whereas in the case of making only the redlight emitting region 501 over the first substrate emit light, referencenumerals 507, 508, and 509 become red light emitting regions. In thecase of making only the blue light emitting region 502 over the secondsubstrate emit light, reference numerals 504 and 507 become blue lightemitting regions, whereas in the case of making only the white lightemitting region 503 over the second substrate emit light, referencenumerals 506 and 509 become white light emitting regions.

Cross sectional views of the pixel structures shown in FIGS. 9A to 9Care shown in FIGS. 10A and 10B and FIGS. 11A and 11B. FIG. 10A is across sectional view along a line A-A′ of FIG. 9A, and FIG. 10B is across sectional view along a line B-B′ of FIG. 9A. FIG. 11A is a crosssectional view along a line C-C′ of FIG. 9A, and FIG. 11B is a crosssectional view along a line D-D′ of FIG. 9A. FIGS. 10A and 10B and FIGS.11A and 11B are the cross sectional views to simply show positionalrelations of the organic light emitting elements provided over the firstsubstrate and the organic light emitting elements provided over thesecond substrate. Therefore, only the first substrate, the organic lightemitting elements provided over the first substrates, the secondsubstrate, and the organic light emitting elements provided over thesecond substrate are shown in FIGS. 10A and 10B and FIGS. 11A and 11B.

In FIG. 10A, a green (G) organic light emitting element 608 and a red(R) organic light emitting element 609 are provided over a firstsubstrate 600 whereas a blue (B) organic light emitting element 613 isprovided over a second substrate 601. As shown in FIG. 10A, the firstsubstrate 600 and the second substrate 601 are attached to each othersuch that the blue organic light emitting element 613 provided over thesecond substrate 601 faces the green organic light emitting element 608and the red organic light emitting element 609 provided over the firstsubstrate.

The green and red organic light emitting elements 608 and 609 providedover the first substrate 600 have a dual emission structure in which thegreen and red organic light emitting elements 608 and 609 emit lighttoward a surface of the first substrate 600 over which the green and redorganic light emitting elements are provided and toward the othersurface of the first substrate 600 opposite to the surface over whichthe organic light emitting elements are provided, i.e., toward thesecond substrate 601. Meanwhile, the blue organic light emitting element613 provided over the second substrate 601 has a top emission structurein which the blue organic light emitting element emits light toward asurface of the second substrate 601 over which the blue organic lightemitting element is provided, i.e., toward the first substrate. Further,arrows indicate the directions of light emitted from the respectiveorganic light emitting elements in FIGS. 10A and 10B and FIGS. 11A and11B.

The green organic light emitting element 608 includes a first electrode602, a second electrode 604, and a layer 603 containing an organiccompound sandwiched between the first electrode 602 and the secondelectrode 604. The red organic light emitting element 609 includes afirst electrode 605, a second electrode 607, and a layer 606 containingan organic compound sandwiched between the first electrode 605 and thesecond electrode 607. The blue organic light emitting element 613includes a first electrode 610, a second electrode 612, and a layer 611containing an organic compound sandwiched between the first electrode610 and the second electrode 612. The white organic light emittingelement 617 includes a first electrode 614, a second electrode 616, anda layer 615 containing an organic compound sandwiched between the firstelectrode 614 and the second electrode 616.

Note that, as materials for forming the first electrodes, the secondelectrodes, and the layers containing an organic compound of therespective organic light emitting elements, the same materials as thoseof the pixel structures shown in FIGS. 6A to 6C, FIGS. 7A and 7B, FIGS.8A and 8B, FIGS. 27A to 27C, and FIGS. 28A and 28B, may be used.

Further, this embodiment mode is not limited to the structure shown inFIGS. 9A to 9C, and positions of the blue light emitting region 502 andthe white light emitting region 503 may be counterchanged.

The overlapping ways of the light emitting regions of the organic lightemitting elements formed over the first substrate and the light emittingregions of the organic light emitting elements formed over the secondsubstrate shown in the pixel structures shown in FIGS. 9A to 9C, FIGS.10A and 10B, and FIGS. 11A and 11B are different from the overlappingways of the pixel structures shown in FIGS. 6A to 6C, FIGS. 7A and 7B,and FIGS. 8A and 8B, and therefore, mixed colors, that is, colors to bedisplayed are also different from one another.

By changing the arrangements of the light emitting regions of theorganic light emitting elements formed over the first substrate and thelight emitting regions of the organic light emitting elements formedover the second substrate, the overlapping ways of colors of the lightemitting regions of the organic light emitting elements formed over thefirst substrate and the light emitting regions of the organic lightemitting elements formed over the second substrates are changed, andtherefore, colors of an image to be displayed can be changed.Consequently, by changing the arrangements of the light emitting regionsof the organic light emitting elements formed over the first substrateand the light emitting regions of the organic light emitting elementsformed over the second substrate in accordance with an image quality tobe required for each image, colors appropriate for each image can bemade.

Embodiment Mode 4

In this embodiment mode, an example of the second structure of thepresent invention will be described. Specifically, this embodiment modewill describe a display device in which a first substrate over which ared (R) organic light emitting element, a green (G) organic lightemitting element, and a blue (B) organic light emitting element areprovided is attached to a second substrate over which a cyan (C) organiclight emitting element, which is a complementary color of red, a magenta(M) organic light emitting element, which is a complementary color ofgreen (G), and a yellow (Y) organic light emitting element, which is acomplementary color of blue (B) are provided, and a display screen isprovided over the first substrate.

In the display device of this embodiment mode, the cyan organic lightemitting element, which is the complementary color of red, the magentaorganic light emitting element, which is the complementary color ofgreen, and the yellow organic light emitting element, which is thecomplementary color of blue, are formed over the second substrate as asubstitute for the white organic light emitting element of EmbodimentMode 1.

FIG. 12A to 12C are diagrams showing an example of pixel structures ofthe display device of this embodiment mode. FIG. 12A shows a pixelstructure as seen from a display screen side (i.e., from a viewer side)in the case where the display screen is formed only over the firstsubstrate. FIG. 12B shows a pixel structure over the first substrate.FIG. 12C shows a pixel structure over the second substrate. By attachingthe first substrate having the pixel structure shown in FIG. 12B to thesecond substrate having the pixel structure shown in FIG. 12C such thatthe organic light emitting elements provided over the both substratesface one another, the pixel structure as shown in FIG. 12A is obtainedas seen from the display screen side, i.e., from a viewer side. FIGS.12B and 12C are top views as seen from each surface of the substratesover which the organic light emitting elements are formed.

In FIG. 12B, reference numeral 700 indicates a red light emitting regionincluding the red (R) organic light emitting element; 701, a green lightemitting region including the green (G) organic light emitting element;and 702, a blue light emitting region including the blue (B) organiclight emitting element.

In FIG. 12C, reference numeral 703 indicates a yellow light emittingregion including the yellow (Y) organic light emitting element; 704, amagenta light emitting region including the magenta (M) organic lightemitting element; and 705, a cyan light emitting region including thecyan (C) organic light emitting element. Note that a wiring and the likeare not shown in FIGS. 12A to 12C so as to simply show overlapped lightemitting regions.

As shown in FIG. 12A, the first and second substrates are attached toeach other such that the red, green, and blue light emitting regions700, 701, and 702 are almost orthogonal to the yellow, magenta, and cyanlight emitting regions 703, 704, and 705. Specifically, the red lightemitting region 700 is overlapped with the yellow light emitting region703, the magenta light emitting region 704, and the cyan light emittingregion 705 respectively, the green light emitting region 701 isoverlapped with the yellow light emitting region 703, the magenta lightemitting region 704, and the cyan light emitting region 705, and theblue light emitting region 702 is overlapped with the yellow lightemitting region 703, the magenta light emitting region 704, and the cyanlight emitting region 705 respectively.

Shaded portions in FIGS. 12A and 12B are light shielding regions since awiring, an element for driving the organic light emitting elements, andthe like are formed over the first substrate. A shaded portion in FIG.12C is a light shielding region since a wiring, an element for drivingthe organic light emitting element, and the like are formed over thesecond substrate. Therefore, when the superimposed first and secondsubstrates are seen from the first substrate side (i.e., from a viewerside), light emitted from the organic light emitting elements formedover the second substrate are shielded at a portion other than the red,green, and blue light emitting regions 700, 701, and 702 formed over thefirst substrate. Accordingly, when a viewer sees the superimposed firstand second substrates, light generated from the yellow, magenta, andcyan light emitting regions 703, 704, and 705 provided over the secondsubstrate, is partly shielded by the light shielding region of the firstsubstrate.

When the red light emitting region 700, the green light emitting region701, and the blue light emitting region 702 provided over the firstsubstrate and the yellow light emitting region 703, the magenta lightemitting region 704, and the cyan light emitting region 705 providedover the second substrate emit light, a viewer sees fifteen differentcolored light emitting regions denoted by reference numerals 706, 707,708, 709, 710, 711, 712, 713, 714, 715, 716, 717, 718, 719, and 720. Inthis case, a mixed colored light emitting region in which red and yelloware mixed, is formed in reference numeral 706. A red light emittingregion is formed in reference numeral 707. A mixed colored lightemitting region in which red and magenta are mixed, is formed inreference numeral 708. Another red light emitting region is formed inreference numeral 709. A mixed colored light emitting region in whichred and cyan are mixed, is formed in reference numeral 710. A mixedcolored light emitting region in which green and yellow are mixed, isformed in reference numeral 711. A green light emitting region is formedin reference numeral 712. A mixed colored light emitting region in whichgreen and magenta are mixed, is formed in reference numeral 713. Anothergreen light emitting region is formed in reference numeral 714. A mixedcolored light emitting region in which green and cyan are mixed, isformed in reference numeral 715. A mixed colored light emitting regionin which blue and yellow are mixed, is formed in reference numeral 716.A blue light emitting region is formed in reference numeral 717. A mixedcolored light emitting region in which blue and magenta are mixed, isformed in reference numeral 718. Another blue light emitting region isformed in reference numeral 719. A mixed colored light emitting regionin which blue and cyan are mixed, is formed in reference numeral 720.

Further, the colors of the light emitting regions over the secondsubstrate are shown in parentheses in reference numerals 706, 708, 710,711, 713, 715, 716, 718, and 720 of FIG. 12A. That is, in referencenumeral 706, “R” and “(Y)” indicate that the red light emitting regionover the first substrate is overlapped with the yellow light emittingregion over the second substrate. In reference numeral 707, “R”indicates that there is only a part of the red light emitting regionprovided over the first substrate. In reference numeral 708, “R” and“(M)” indicate that the red light emitting region over the firstsubstrate is overlapped with the magenta light emitting region over thesecond substrate. In reference numeral 709, “R” indicates that there isonly a part of the red light emitting region provided over the firstsubstrate. In reference numeral 710, “R” and “(C)” indicate that the redlight emitting region over the first substrate is overlapped with thecyan light emitting region over the second substrate. In referencenumeral 711, “G” and “(Y)” indicate that the green light emitting regionover the first substrate is overlapped with the yellow light emittingregion over the second substrate. In reference numeral 712, “G”indicates that there is only a part of the green light emitting regionprovided over the first substrate. In reference numeral 713, “G” and“(M)” indicate that the green light emitting region over the firstsubstrate is overlapped with the magenta light emitting region over thesecond substrate. In reference numeral 714, “G” indicates that there isonly a part of the green light emitting region provided over the firstsubstrate. In reference numeral 715, “G” and “(C)” indicate that thegreen light emitting region over the first substrate is overlapped withthe cyan light emitting region over the second substrate. In referencenumeral 716, “B” and “(Y)” indicate that the blue light emitting regionover the first substrate is overlapped with the yellow light emittingregion over the second substrate. In reference numeral 717, “B”indicates that there is only a part of the blue light emitting regionprovided over the first substrate. In reference numeral 718, “B” and“(M)” indicate that the blue light emitting region over the firstsubstrate is overlapped with the magenta light emitting region over thesecond substrate. In reference numeral 719, “B” indicates that there isonly a part of the blue light emitting region provided over the firstsubstrate. In reference numeral 720, “B” and “(C)” indicate that theblue light emitting region over the first substrate is overlapped withthe cyan light emitting region over the second substrate.

In the case of making only the red light emitting region 700 over thefirst substrate emit light, reference numerals 706, 707, 708, 709, and710 become red light emitting regions. In the case of making only thegreen light emitting region 701 over the first substrate emit light,reference numerals 711, 712, 713, 714, and 715 become green lightemitting regions. In the case of making only the blue light emittingregion 702 over the first substrate emit light, reference numerals 716,717, 718, 719, and 720 become blue light emitting regions. In the caseof making only the yellow light emitting region 703 over the secondsubstrate emit light, reference numerals 706, 711, and 716 become yellowlight emitting regions. In the case of making only the magenta lightemitting region 704 over the second substrate emit light, referencenumerals 708, 713, and 718 become magenta light emitting regions. In thecase of making only the cyan light emitting region 705 over the secondsubstrate emit light, reference numerals 710, 715, and 720 become cyanlight emitting regions.

Cross sectional views of the pixel structures shown in FIGS. 12A to 12Care shown in FIGS. 13A and 13B. FIG. 13A is a cross sectional view alonga line A-A′ of FIG. 12A, and FIG. 13B is a cross sectional view along aline B-B′ of FIG. 12A. FIGS. 13A and 13B are schematic cross sectionalviews simply showing cross sectional structures of a display deviceaccording to the present invention, and each of the views shows only afirst substrate, red, green, blue organic light emitting elementsprovided over the first substrate, a second substrate, and yellow,magenta, and cyan organic light emitting elements provided over thesecond substrate.

In FIG. 13A, a red organic light emitting element 811, a green organiclight emitting element 812, and a blue organic light emitting element813 are provided over a first substrate 800 whereas a magenta organiclight emitting element 828 is provided over a second substrate 801. Themagenta organic light emitting element 828 provided over the secondsubstrate faces the red organic light emitting element 811, the greenorganic light emitting element 812, and the blue organic light emittingelement 813.

In FIG. 13B, the red organic light emitting element 811 is provided overthe first substrate 800 whereas a yellow organic light emitting element827, the magenta organic light emitting element 828, and a cyan organiclight emitting element 829 are provided over the second substrate 801.

The red organic light emitting element 811 includes a first electrode802, a second electrode 804, and a layer 803 containing an organiccompound sandwiched between the first electrode 802 and the secondelectrode 804. The green organic light emitting element 812 includes afirst electrode 805, a second electrode 807, and a layer 806 containingan organic compound sandwiched between the first electrode 805 and thesecond electrode 807. The blue organic light emitting element 813includes a first electrode 808, a second electrode 810, and a layer 809containing an organic compound sandwiched between the first electrode808 and the second electrode 810.

The yellow organic light emitting element 827 includes a first electrode818, a second electrode 820, and a layer 819 containing an organiccompound sandwiched between the first electrode 818 and the secondelectrode 820. The magenta organic light emitting element 828 includes afirst electrode 821, a second electrode 823, and a layer 822 containingan organic compound sandwiched between the first electrode 821 and thesecond electrode 823. The cyan organic light emitting element 829includes a first electrode 824, a second electrode 826, and a layer 825containing an organic compound sandwiched between the first electrode824 and the second electrode 826.

In FIGS. 13A and 13B, arrows indicate the directions of light emittedfrom the respective organic light emitting elements. In FIGS. 13A and13B, images are displayed over the first substrate. That is, a displayscreen is provided only over the first substrate. Accordingly, the red,green, and blue organic light emitting elements 811, 812, and 813provided over the first substrate have a dual emission structure,whereas the yellow, magenta, and cyan organic light emitting elements827, 828, and 829 provided over the second substrate have a top emissiontype structure. Therefore, the first and second electrodes of theorganic light emitting elements provided over the first substrate areformed using transparent conducive films. The second electrodes of theorganic light emitting elements provided over the second substrate arealso formed using a transparent conductive film. Note that the firstelectrodes of the organic light emitting elements provided over thesecond substrate are preferably formed using reflecting electrodes so asto reflect light emitted toward the second substrates from the organiclight emitting elements provided over the first substrate toward thefirst substrate.

Note that the materials described in Embodiment Mode 1 may be used asmaterials for forming the reflecting electrodes and the transparentconductive films.

By using the above mentioned structure, yellow, magenta, and cyan can bemixed with red, green, and blue to be displayed. Thus, colors whichcannot be expressed only by the three colors of red, green, and blue,can be expressed.

Note that the pixel structures shown in FIGS. 12A to 12C and FIGS. 13Aand 13B are just examples, and the present invention is not limitedthereto. In this embodiment mode, the example of forming the cyan,magenta, and yellow organic light emitting elements is shown in thisembodiment mode; however, the number of colors of organic light emittingelements to be formed are not limited to the three colors.Alternatively, one or two colored organic light emitting elementsselected from cyan, magenta, and yellow may be formed. Further, thecolors of organic light emitting elements to be formed are not limitedto cyan, magenta, and yellow which are the complementary colors of red,green, and blue. An organic light emitting element having a color otherthan cyan, magenta, yellow, red, green, and blue may be provided so longas it is a color which can widen a range of colors which can bedisplayed. Accordingly, any organic light emitting element may be formedso long as it emits light with a color having a chromaticity coordinateoutside of a triangle of a red chromaticity coordinate, a greenchromaticity coordinate, and a blue chromaticity coordinate.

The arrangements of the yellow, magenta, and cyan organic light emittingelements are not particularly limited to the arrangements of FIGS. 12Ato 12C. The light emitting regions of the organic light emittingelements provided over the first substrate are overlapped with the lightemitting regions of the organic light emitting elements provided overthe second substrate such that they are almost orthogonal to one anotherin FIGS. 12A to 12C; however, the present invention is not limitedthereto. Alternatively, the light emitting regions of the organic lightemitting elements provided over the first and second substrates may bearranged in parallel such that one color of the organic light emittingelements provided over the first substrate faces one color of theorganic light emitting elements provided over the second substrate.However, in a case where the light emitting regions of the organic lightemitting elements provided over the first and second substrates arearranged in the same manner as FIGS. 12A to 12C, the three colors oforganic light emitting elements provided over the second substrate areuniformly overlapped with the one color of the organic light emittingelement provided over the first substrate, and therefore, an image canbe displayed with uniform colors.

Note that only the case where the red, green, and blue organic lightemitting elements are provided over the first substrate, the yellow,magenta, and cyan organic light emitting elements are provided over thesecond substrate, and the display screen is provided over the firstsubstrate, is described in this embodiment mode; however, the presentinvention is not limited thereto.

Further, the positions of the organic light emitting elements providedover the first substrate and the organic light emitting elementsprovided over the second substrate may be counterchanged. Furthermore, awhite organic light emitting element may be provided over the firstsubstrate and yellow, magenta, and cyan organic light emitting elementsmay be provided over the second substrate.

Moreover, display screens may be provided over both of the first andsecond substrates. In this case, the organic light emitting elementsprovided over the first and second substrates may have a dual emissionstructure. That is, the first and second electrodes of the organic lightemitting elements provided over the first and second substrates maybeformed using transparent conductive films.

Embodiment Mode 5

In this embodiment mode, an example of the second structure of thepresent invention will be described. Specifically, a display device inwhich a red organic light emitting element is formed over a firstsubstrate, a blue organic light emitting element is formed over a secondsubstrate, a green organic light emitting element is formed over eitherthe first substrate or the second substrate, a one colored organic lightemitting element selected from a complementary color of red, acomplementary color of green, and a complementary color of blue isformed over either the first substrate or the second substrate, areas oflight emitting regions of the red and blue organic light emittingelements set larger than an area of a light emitting region of the greenorganic light emitting element, will be described.

The display device in which the red organic light emitting element andeither the green organic light emitting element or the white organiclight emitting element are provided over the first substrate, the blueorganic light emitting element and either the green light emittingelement or the white organic light emitting element are provided overthe second substrate, the areas of the light emitting regions of the redand blue organic light emitting elements are set larger than the area ofthe light emitting region of the green organic light emitting element,are described in Embodiment Mode 3. In this structure of Embodiment Mode3, when a one colored organic light emitting element selected from thecomplementary colors of red, green, and blue is provided as a substitutefor the white organic light emitting element, the fourth structure ofthe present invention can be implemented.

Since the visibility of red and blue is lower than the visibility ofgreen, by making areas of light emitting regions of red and blue organiclight emitting elements larger than an area of a light emitting regionof a green organic light emitting element, it is possible to balancered, green, and blue colors according to the structure of thisembodiment mode. In addition, since the one colored organic lightemitting element selected from the complementary colors of red, green,and blue is provided, colors which cannot be expressed only by red,green, and blue organic light emitting elements, can be expressed,making it possible to widen the range of colors to be reproduced. Inaddition, since the two colored organic light emitting elements areprovided over each of the first and second substrates, as compared to acase of providing three colored organic light emitting elements over asubstrate while having the same number of pixels provided over thesubstrate, the number of elements required for driving the organic lightemitting elements provided over each dot can be reduced. As aconsequence, aperture ratio can be improved.

Note that a color selected from the complementary colors of red, green,and blue may be determined in accordance with an image quality to berequired. Moreover, the above described effect can be obtained even in acase of using a color other than the complementary colors of red, green,and blue so long as it is a color which can widen the range of atriangle of a red chromaticity coordinate, a green chromaticitycoordinate, and a blue chromaticity coordinate. Accordingly, any coloredorganic light emitting element is allowable so long as it can emit lightwith a color having a chromaticity coordinate outside of the range ofthe triangle of the red, green, and blue chromaticity coordinates otherthan the complementary colors of red, green, and blue.

Embodiment Mode 6

In this embodiment mode, an example of the third structure of thepresent invention will be described. Specifically, a display device inwhich red, green, and blue organic light emitting elements are providedover a first substrate, red, green, and blue organic light emittingelements are provided over a second substrate, and different coloredorganic light emitting elements provided over the first and secondsubstrates are overlapped with one another, will be described withreference to FIGS. 29A to 29C, and FIG. 30.

Pixel structures of a display device of this embodiment mode are shownin FIGS. 29A to 29C. FIG. 29A shows a pixel structure as seen from adisplay screen side, i.e., from a viewer side, FIG. 29B shows a pixelstructure of a first substrate, and FIG. 29C shows a pixel structure ofa second substrate. When the first substrate having the pixel structureshown in FIG. 29B is overlapped with the second substrate having thepixel structure shown in FIG. 29C such that the organic light emittingelements provided over the first and second substrates face one another,the pixel structure as shown in FIG. 29A can be obtained as seen fromthe display screen side, i.e., from a viewer side. FIGS. 29B and 29C aretop views as seen from the surfaces of the first and second substratesover which the organic light emitting elements are provided. Note that,FIG. 29A to 29C show an example where the display screen is providedonly over the first substrate.

In FIG. 29B, reference numeral 3100 indicates a red light emittingregion including a red organic light emitting element; 3101, a greenlight emitting region including a green organic light emitting element;and 3102, a blue light emitting region including a blue organic lightemitting element. In FIG. 29C, reference numeral 3103 indicates a bluelight emitting region including a blue organic light emitting element;3104, a red light emitting region including a red organic light emittingelement; and 3105, a green light emitting region including a greenorganic light emitting element. Note that, in order to simply show theoverlapped light emitting regions, a wiring and the like are not shownin FIGS. 29A to 29C, and only the light emitting regions are showntherein.

Shaded portions in FIGS. 29A and 29B are light shielding regions since awiring, an element for driving the organic light emitting elements, andthe like are formed over the first substrate. A shaded portion in FIG.29C is a light shielding region since a wiring, an element for drivingthe organic light emitting element, and the like are formed over thesecond substrate. In this embodiment mode, the light emitting regionsformed over the first substrate has almost the same size as the lightemitting regions provided over the second substrate, and these lightemitting regions are arranged to overlap with one another at the samepositions. Accordingly, the light shielding region of the firstsubstrate is formed at almost the same position as the light shieldingregion of the second substrate.

When the red light emitting region 3100, the green light emitting region3101, and the blue light emitting region 3102 provided over the firstsubstrate and the blue light emitting region 3103, the red lightemitting region 3104, and the green light emitting region 3105 providedover the second substrate emit light, a viewer sees three differentcolored light emitting regions denoted by reference numerals 3106, 3107,and 3108. In this case, in reference numeral 3106, a mixed colored lightemitting region in which red and blue are mixed, is formed. In referencenumeral 3107, a mixed colored light emitting region in which green andred are mixed, is formed. In reference numeral 3108, a mixed coloredlight emitting region in which blue and green are mixed, is formed.

Further, the colors of the light emitting regions of the secondsubstrate are shown in parentheses in reference numerals 3106, 3107, and3108 of FIG. 29A since the light emitting regions of the first andsecond substrates are overlapped with one another at the same positions.That is, in reference numeral 3106, “R” and “(B)” indicate that the redlight emitting region of the first substrate is overlapped with the bluelight emitting region of the second substrate. In reference numeral3107, “G” and “(R)” indicate that the green light emitting region of thefirst substrate is overlapped with the red light emitting region of thesecond substrate. In reference numeral 3108, “B” and “(G)” indicate thatthe blue light emitting region of the first substrate is overlapped withthe green light emitting region of the second substrate.

In the case of making only the red light emitting region 3100 over thefirst substrate emit light, reference numeral 3106 becomes a red lightemitting region. In the case of making only the green light emittingregion 3101 over the first substrate emit light, reference numeral 3107becomes a green light emitting region. In the case of making only theblue light emitting region 3102 over the first substrate emit light,reference numeral 3108 becomes a blue light emitting region. In the caseof making only the blue light emitting region 3103 over the secondsubstrate emit light, reference numeral 3106 becomes a blue lightemitting region. In the case of making only the red light emittingregion 3104 over the second substrate emit light, reference numeral 3107becomes a red light emitting region. In the case of making only thegreen light emitting region 3105 over the second substrate emit light,reference numeral 3108 becomes a green light emitting region.

FIG. 30 is a cross sectional view along a line A-A′ of FIG. 29A. FIG. 30is a schematic cross sectional view to simply show a cross sectionalstructure of a display device according to the present invention. Onlythe red, green, and blue organic light emitting elements provided overthe first substrate and the red, green, and blue organic light emittingelements provided over the second substrate, are shown.

In FIG. 30, a red (R) organic light emitting element 1011, a green (G)organic light emitting element 1012, and a blue (B) organic lightemitting element 1013 are provided over a first substrate 1000 whereas ablue organic light emitting element 1027, a red organic light emittingelement 1028, and a green organic light emitting element 1029 areprovided over a second substrate 1001.

The organic light emitting elements 1011, 1012, and 1013 provided overthe first substrate 1000 have a dual emission structure in which theorganic light emitting elements emit light toward a surface of the firstsubstrate 1000 over which the organic light emitting elements areprovided and toward the other surface of the first substrate opposite tothe surface of the first substrate over which the organic light emittingelements are provided, i.e., toward the second substrate 1001.Meanwhile, the organic light emitting elements 1027, 1028, and 1029provided over the second substrate 1001 has a top emission structure inwhich the organic light emitting elements emit light toward a surface ofthe second substrate over which the organic light emitting elements areprovided, i.e., toward the first substrate. Further, arrows indicate thedirections of light emitted from the respective organic light emittingelements in FIG. 30.

The red organic light emitting element 1011 includes a first electrode1002, a second electrode 1004, and a layer 1003 containing an organiccompound sandwiched between the first electrode 1002 and the secondelectrode 1004. The green organic light emitting element 1012 includes afirst electrode 1005, a second electrode 1007, and a layer 1006containing an organic compound sandwiched between the first electrode1005 and the second electrode 1007. The blue organic light emittingelement 1013 includes a first electrode 1008, a second electrode 1010,and a layer 1009 containing an organic compound sandwiched between thefirst electrode 1008 and the second electrode 1010. The blue organiclight emitting element 1027 includes a first electrode 1017, a secondelectrode 1019, and a layer 1018 containing an organic compoundsandwiched between the first electrode 1017 and the second electrode1019. The red organic light emitting element 1028 includes a firstelectrode 1020, a second electrode 1022, and a layer 1021 containing anorganic compound sandwiched between the first electrode 1020 and thesecond electrode 1022. The green organic light emitting element 1029includes a first electrode 1023, a second electrode 1025, and a layer1024 containing an organic compound sandwiched between the firstelectrode 1023 and the second electrode 1025.

Note that the materials described in Embodiment Mode 1 may be used asmaterials of the first and second electrodes of the respective organiclight emitting elements.

As shown in FIG. 30, the first substrate 1000 and the second substrate1001 are overlapped with each other such that the red organic lightemitting element 1011 formed over the first substrate faces the blueorganic light emitting element 1027 formed over the second substrate,the green organic light emitting element 1012 formed over the firstsubstrate faces the red organic light emitting element 1028 formed overthe second substrate, and the blue organic light emitting element 1013formed over the first substrate faces the green organic light emittingelement 1029 formed over the second substrate.

Overlapping the different colored organic light emitting elements oneanother makes it possible to improve image resolution performance.

This point will be described with reference to FIG. 16 and FIG. 17. FIG.16 is a top view of a portion where dots are aligned in five rows andseven columns in a normal display device for color display in a casewhere one pixel includes red, green, and blue dots. In FIG. 16, Rindicates a red light emitting region (a red dot) including a redorganic light emitting element, G indicates a green light emittingregion (a green dot) including a green organic light emitting element,and B indicates a blue light emitting region (a blue dot) including ablue organic light emitting element.

For example, in order to display a blue diagonal line, as shown in FIG.16, blue dots 1100, 1101, and 1102 emit light. Note that, in FIG. 16,shaded dots represent dots which emit light whereas dots which are notshaded, represent dots which emit no light.

FIG. 17 is a top view as seen from a display screen of a portion wheredots are aligned in five rows and seven columns over the first substrateof the display device of this embodiment mode. Note that, as shown inFIGS. 29A to 29C, since dots formed over the first substrate and dotsformed over the second substrate are recognized as being overlapped withone another at the same positions as seen from a viewer side, colors ofthe dots formed over the second substrate are shown in parentheses inFIG. 17.

Specifically, in FIG. 17, R indicates a red light emitting region (a reddot) including a red organic light emitting element provided over thefirst substrate, G indicates a green light emitting region (a green dot)including a green organic light emitting element provided over the firstsubstrate, and B indicates a blue light emitting region (a blue dot)including a blue organic light emitting element provided over the firstsubstrate. Further, (R) indicates a red light emitting region (a reddot) including a red organic light emitting element provided over thesecond substrate, (G) indicates a green light emitting region (a greendot) including a green organic light emitting element provided over thesecond substrate, and (B) indicates a blue light emitting region (a bluedot) including a blue organic light emitting element provided over thesecond substrate. For example, with respect to a dot 1100, a dotprovided over the first substrate at the position of the dot 1100 isblue and a dot provided over the second substrate at the position of thedot 1100 (which is overlapped with the dot provided over the firstsubstrate at the same position as seen from a viewer side) is green.

In order to display a blue diagonal line on the display device of thisembodiment mode as well as the normal display device shown in FIG. 16,as shown in FIG. 17, blue dots 1103 and 1104 emit light in addition tothe blue dots 1100, 1101, and 1102. Note that, in FIG. 17, shaded dotsrepresent dots which emit light whereas dots which are not shaded,represent dots which emit no light. Among the dots emitting light, thedots 1100, 1101, and 1102 provided over the first substrate are markedby upward-shaded lines whereas the dots 1103 and 1104 provided over thesecond substrate are marked by downward-shaded lines.

As known form FIG. 16 and FIG. 17, image resolution performance of FIG.17 is higher than that of FIG. 16. That is, when the organic lightemitting elements provided over the first and second substrates arearranged such that the different colored organic light emitting elementsare overlapped with one another, image resolution performance can beimproved, thereby displaying a higher-resolution image.

Further, FIGS. 29A to 29C and FIG. 30 show the case where the dotsprovided over the first substrate and the dots provided over the secondsubstrate are overlapped with one another at the same positions;however, the present invention is not limited to this structure. In acase where the organic light emitting elements provided over the firstand second substrates are arranged such that the different coloredorganic light emitting elements are overlapped one another, the imageresolution performance can be improved. That is, when the organic lightemitting elements provided over the first and second substrates areprovided such that the different colored organic light emitting elementsare at least partly overlapped with one another as seen from a viewerside, an effect of improving image resolution performance can beobtained. Accordingly, the light emitting regions of the organic lightemitting elements provided over the first and second substrates may bearranged such that the different colored light emitting regions providedover the first and second substrates are partly overlapped with oneanother.

A case where light emitting regions of different colored organic lightemitting elements provided over first and second substrates are partlyoverlapped with one another, will be described with reference to FIGS.14A to 14C and FIG. 15.

FIGS. 14A to 14C show pixel structures of a display device according tothis embodiment mode. FIG. 14A shows a pixel structure as seen from thedisplay screen side, that is, from a viewer side. FIG. 14B shows a pixelstructure of the first substrate, and FIG. 14C shows a pixel structureof the second substrate. When the first substrate having the pixelstructure shown in FIG. 14B is overlapped with the second substratehaving the pixel structure shown in FIG. 14C such that the organic lightemitting elements provided over the first and second substrates face oneanother, the pixel structure as shown in FIG. 14A can be obtained asseen from a display screen side, i.e., from a viewer side. Each of FIGS.14B and 14C is a top view as seen from the surface provided with theorganic light emitting elements. Note that, FIGS. 14A to 14C show a casewhere a display screen is provided only over the first substrate.

In FIG. 14B, reference numeral 900 indicates a red light emitting regionincluding a red organic light emitting element; 901, a green lightemitting region including a green organic light emitting element; and902, a blue light emitting region including a blue organic lightemitting element. In FIG. 14C, reference numeral 903 indicates a part ofa green light emitting region including a green organic light emittingelement; 904, a blue light emitting region including a blue organiclight emitting element; 905, a red light emitting region including a redorganic light emitting element; and 906, a part of a green lightemitting region including a green organic light emitting element.

Note that FIG. 14A shows a portion corresponding to one pixel over thefirst substrate. Therefore, FIG. 14C shows only a part of the greenlight emitting region 903 and a part of the green light emitting region906 over the second substrate, respectively.

Further, a wiring and the like are not shown in FIGS. 14A to 14C andonly the light emitting regions are shown therein so as to simply showthe overlapped light emitting regions. Furthermore, FIGS. 14A to 14Cshow a case where a display screen is provided only over the firstsubstrate.

Shaded portions in FIGS. 14A and 14B are light shielding regions since awiring, an element for driving the organic light emitting elements, andthe like are formed over the first substrate. A shaded portion in FIG.14C is also a light shielding region since a wiring, an element fordriving the organic light emitting elements, and the like are formedover the second substrate. Therefore, when a viewer sees the firstsubstrate overlapped with the second substrate from the first substrateside, light emitted from the organic light emitting elements formed overthe second substrate is shielded in a region other than the red lightemitting region 900, the green light emitting region 901, and the bluelight emitting region 902 provided over the first substrate. Thus, whena viewer sees the superimposed first and second substrates from thefirst substrate side, light emitted from the green, blue, and red lightemitting regions 903, 904, 905, and 906 provided over the secondsubstrate is partly shielded by the light shielding region of the firstsubstrate.

When the red light emitting region 900, the green light emitting region901, and the blue light emitting region 902 provided over the firstsubstrate, and the part of the green light emitting region 903, the bluelight emitting region 904, the red light emitting region 905, and thepart of the green light emitting region 906 provided over the secondsubstrate emit light, a viewer sees nine different colored lightemitting regions denoted by reference numerals 907, 908, 909, 910, 911,912, 913, 914, and 915. In this case, a mixed colored light emittingregion in which red and green are mixed, is formed in reference numeral907. A red light emitting region is formed in reference numeral 908. Amixed colored light emitting region in which red and blue are mixed, isformed in reference numeral 909. A mixed colored light emitting regionin which green and blue are mixed, is formed in reference numeral 910. Agreen light emitting region is formed in reference numeral 911. A mixedcolored light emitting region in which green and red are mixed, isformed in reference numeral 912. A mixed colored light emitting regionin which blue and red are mixed, is formed in reference numeral 913. Ablue light emitting region is formed in reference numeral 914. A mixedcolored light emitting region in which blue and green are mixed, isformed in reference numeral 915.

Further, the colors of the light emitting regions over the secondsubstrate are shown in parentheses in reference numerals 907, 909, 910,912, 913, and 915 of FIG. 14A. Specifically, in reference numeral 907,“R” and “(G)” indicate that the red light emitting region over the firstsubstrate is overlapped with the green light emitting region over thesecond substrate. In reference numeral 908, “R” indicates that there isonly a part of the red light emitting region provided over the firstsubstrate. In reference numeral 909, “R” and “(B)” indicate that the redlight emitting region over the first substrate is overlapped with theblue light emitting region over the second substrate. In referencenumeral 910, “G” and “(B)” indicate that the green light emitting regionover the first substrate is overlapped with the blue light emittingregion over the second substrate. In reference numeral 911, “G”indicates that there is only a part of the green light emitting regionprovided over the first substrate. In reference numeral 912, “G” and“(R)” indicate that the green light emitting region over the firstsubstrate is overlapped with the red light emitting region over thesecond substrate. In reference numeral 913, “B” and “(R)” indicate thatthe blue light emitting region over the first substrate is overlappedwith the red light emitting region over the second substrate. Inreference numeral 914, “B” indicates that there is only a part of theblue light emitting region provided over the first substrate. Inreference numeral 915, “B” and “(G)” indicate that the blue lightemitting region over the first substrate is overlapped with the greenlight emitting region over the second substrate.

In the case of making only the red light emitting region 900 over thefirst substrate emit light, reference numerals 907, 908, and 909 becomered light emitting regions. In the case of making only the green lightemitting region 901 over the first substrate emit light, referencenumerals 910, 911, and 912 become green light emitting regions. In thecase of making only the blue light emitting region 902 over the firstsubstrate emit light, reference numerals 913, 914, and 915 become bluelight emitting regions. In the case of making only the green lightemitting region 903 over the second substrate emit light, referencenumeral 907 becomes a green light emitting region. In the case of makingonly the blue light emitting region 904 over the second substrate emitlight, reference numerals 909 and 910 become blue light emittingregions. In the case of making only the red light emitting region 905over the second substrate emit light, reference numerals 912 and 913become red light emitting regions. In the case of making only the greenlight emitting region 906 over the second substrate emit light,reference numeral 915 becomes a green light emitting region.

Cross sectional views along a line A-A′ of FIG. 14A is shown in FIG. 15.FIG. 15 is a schematic cross sectional view simply showing a crosssectional structure of the display device according to the presentinvention, and shows only a first substrate, red, green, and blueorganic light emitting elements provided over the first substrate, asecond substrate, and red, green, and blue organic light emittingelements provided over the second substrate.

In FIG. 15, a red (R) organic light emitting element 1011, a green (G)organic light emitting element 1012, and a blue (B) organic lightemitting element 1013 are provided over a first substrate 1000 whereasgreen organic light emitting elements 1026 and 1029, a blue organiclight emitting element 1027, and a red organic light emitting element1028 are provided over a second substrate 1001. Note that only a part ofthe green organic light emitting element 1026 and a part of the greenorganic light emitting element 1029 are shown in FIG. 15.

In FIG. 15, the same portions as those of FIG. 30 are denoted by thesame reference numerals. In FIG. 15, reference numeral 1026 indicates agreen organic light emitting element including a first electrode 1014, asecond electrode 1016, and a layer 1015 containing an organic compoundsandwiched between the first electrode 1014 and the second electrode1016.

As shown in FIG. 15, the first substrate 1000 and the second substrate1001 are overlapped with each other such that the red organic lightemitting element 1011 provided over the first substrate faces a part ofthe green organic light emitting element 1026 and a part of the blueorganic light emitting element 1027 provided over the second substrate,the green organic light emitting element 1012 provided over the firstsubstrate faces a part of the blue organic light emitting element 1027and a part of the red organic light emitting element 1028 provided overthe second substrate, and the blue organic light emitting element 1013provided over the first substrate faces a part of the red organic lightemitting element 1028 and a part of the green organic light emittingelement 1029 provided over the second substrate. That is, the organiclight emitting elements provided over the first and second substratesare arranged such that the different colored organic light emittingelements are partly overlapped with one another.

By overlapping the different colored organic light emitting elementswith one another in such a manner, image resolution performance can beimproved.

Embodiment Mode 7

In this embodiment mode, the fourth structure of the present inventionwill be described. Specifically, an example where red, green, and blueorganic light emitting elements are provided over one of first andsecond substrates and a blue organic light emitting element is providedover the other substrate, will be described. In order to form astructure in which the red, green, and blue organic light emittingelements are provided over one of the first and second substrates andthe blue organic light emitting element is provided over the othersubstrate, in the structure of Embodiment Mode 1, a blue organic lightemitting element may be provided as a substitute for the white organiclight emitting element 120 provided over the second substrate.

In the case of providing the white organic light emitting element overthe second substrate as shown in Embodiment Mode 1, since the brightnessof the entire display screen is necessary to be made uniform, the lightemitting regions of the red, green, and blue organic light emittingelements provided over the first substrate are uniformly overlapped withthe white organic light emitting region. Meanwhile, in the case ofproviding a blue organic light emitting element over the secondsubstrate, the blue organic light emitting element formed over thesecond substrate is provided to compensate luminance of the blue organiclight emitting element formed over the first substrate, and therefore,the light emitting regions of the red, green, and blue organic lightemitting elements provided over the first substrate are not necessary tobe uniformly overlapped with the blue organic light emitting elementprovided over the second substrate. For example, the blue organic lightemitting element may be provided over the second substrate to beoverlapped with only the blue organic light emitting element providedover the first substrate.

Note that, an organic light emitting element provided over the secondsubstrate is not limited to the blue organic light emitting element. Forexample, in a case where the red organic light emitting element providedover the first substrate does not have sufficient luminance, another redorganic light emitting element may be provided over the secondsubstrate. Alternatively, in a case where the green organic lightemitting element provided over the first substrate does not havesufficient luminance, another green organic light emitting element maybe provided over the second substrate.

Embodiment 1

In this embodiment, an example of pixel structures of the secondstructure of the present invention, which is different from EmbodimentMode 4, will be described. FIGS. 20A to 20C show pixel structures of adisplay device, which are different from those of Embodiment Mode 4.FIG. 20A shows a pixel structure as seen from a display screen side.FIG. 20B shows a pixel structure over the first substrate. FIG. 20Cshows a pixel structure over the second substrate. When the firstsubstrate having the pixel structure shown in FIG. 20B is overlappedwith the second substrate having the pixel structure shown in FIG. 20Csuch that organic light emitting elements provided over the first andsecond substrates face one another, the pixel structure as shown in FIG.20A is obtained as seen from the display screen side, i.e., from aviewer side. Note that the display screen is provided only over thefirst substrate. Each of FIGS. 20B and 20C is a top view as seen from asurface of each substrate over which the organic light emitting elementsare formed.

In FIG. 20B, reference numerals 1400, 1403, and 1406 indicate red lightemitting regions including red (R) organic light emitting elements;1401, 1404, and 1407, green light emitting regions including green (G)organic light emitting elements; and 1402, 1405, and 1408, blue lightemitting regions including blue (B) organic light emitting elements.

In FIG. 20C, reference numeral 1410 indicates a cyan light emittingregion including a cyan (C) organic light emitting element; 1411, amagenta light emitting region including a magenta (M) organic lightemitting element; and 1412, a yellow light emitting region including ayellow (Y) organic light emitting element. Note that a wiring and thelike are not shown in FIGS. 20A to 20C so as to simply show overlappedlight emitting regions.

As shown in FIG. 20, the red light emitting region 1400, the green lightemitting region 1401, and the blue light emitting region 1402 areoverlapped with the cyan light emitting region 1410. The red lightemitting region 1403, the green light emitting region 1404, and the bluelight emitting region 1405 are overlapped with the magenta lightemitting region 1411. The red light emitting region 1406, the greenlight emitting region 1407, and the blue light emitting region 1408 areoverlapped with the yellow light emitting region 1412. According to thisstructure, colors which cannot be expressed only by red, green, andblue, can be expressed.

Shaded portions in FIGS. 20A and 20B are light shielding regions since awiring, an element for driving the organic light emitting elements, andthe like are formed over the first substrate. A shaded portion in FIG.20C is a light shielding region since a wiring, an element for drivingthe organic light emitting elements, and the like are formed over thesecond substrate. Therefore, when the superimposed first and secondsubstrates are seen from the first substrate side (i.e., from a viewerside), light emitted from the organic light emitting elements formedover the second substrate is shielded at a portion other than the redlight emitting regions 1400, 1403, and 1406, the green light emittingregions 1401, 1404, and 1407, and the blue light emitting regions 1402,1405, and 1408 formed over the first substrate. Accordingly, when thesuperimposed first and second substrates are seen from the viewer side,light emitted from the cyan, magenta, and yellow light emitting region1410, 1411, and 1412, is partly shielded by the light shielding regionof the first substrate.

When the red light emitting regions 1400, 1403, and 1406, the greenlight emitting regions 1401, 1404, and 1407, and the blue light emittingregions 1402, 1405, and 1408 provided over the first substrate emitlight while the cyan light emitting region 1410, the magenta lightemitting region 1411, and the yellow light emitting region 1412 providedover the second substrate emit light, a viewer sees nine differentcolored light emitting regions denoted by reference numerals 1413, 1414,1415, 1416, 1417, 1418, 1419, 1420, and 1421. In this case, a mixedcolored light emitting region in which red and cyan are mixed, is formedin reference numeral 1413. A mixed colored light emitting region inwhich green and cyan are mixed, is formed in reference numeral 1414. Amixed colored light emitting region in which blue and cyan are mixed, isformed in reference numeral 1415. A mixed colored light emitting regionin which red and magenta are mixed, is formed in reference numeral 1416.A mixed colored light emitting region in which green and magenta aremixed, is formed in reference numeral 1417. A mixed colored lightemitting region in which blue and magenta are mixed, is formed inreference numeral 1418. A mixed colored light emitting region in whichred and yellow are mixed, is formed in reference numeral 1419. A mixedcolored light emitting region in which green and yellow are mixed, isformed in reference numeral 1420. A mixed colored light emitting regionin which blue and yellow are mixed, is formed in reference numeral 1421.

Further, the colors of the light emitting regions over the secondsubstrate are shown in parentheses in reference numerals 1413, 1414,1415, 1416, 1417, 1418, 1419, 1420, and 1421 of FIG. 20A. Specifically,in reference numeral 1413, “R” and “(C)” indicate that the red lightemitting region over the first substrate is overlapped with the cyanlight emitting region over the second substrate. In reference numeral1414, “G” and “(C)” indicate that the green light emitting region overthe first substrate is overlapped with the cyan light emitting regionover the second substrate. In reference numeral 1415, “B” and “(C)”indicate that the blue light emitting region over the first substrate isoverlapped with the cyan light emitting region over the secondsubstrate. In reference numeral 1416, “R” and “(M)” indicate that thered light emitting region over the first substrate is overlapped withthe magenta light emitting region over the second substrate. Inreference numeral 1417, “G” and “(M)” indicate that the green lightemitting region over the first substrate is overlapped with the magentalight emitting region over the second substrate. In reference numeral1418, “B” and “(M)” indicate that the blue light emitting region overthe first substrate is overlapped with the magenta light emitting regionover the second substrate. In reference numeral 1419, “R” and “(Y)”indicate that the red light emitting region over the first substrate isoverlapped with the yellow light emitting region over the secondsubstrate. In reference numeral 1420, “G” and “(Y)” indicate that thegreen light emitting region over the first substrate is overlapped withthe yellow light emitting region over the second substrate. In referencenumeral 1421, “B” and “(Y)” indicate that the blue light emitting regionover the first substrate is overlapped with the yellow light emittingregion over the second substrate.

In the case of making only the red light emitting region 1400 over thefirst substrate emit light, reference numeral 1413 become a red lightemitting region. In the case of making only the green light emittingregion 1401 over the first substrate emit light, reference numeral 1414become a green light emitting region. In the case of making only theblue light emitting region 1402 over the first substrate emit light,reference numeral 1415 become a blue light emitting region. In the caseof making only the cyan light emitting region 1410 over the secondsubstrate emit light, reference numerals 1413, 1414, and 1415 becomecyan light emitting regions. In the case of making only the magentalight emitting region 1411 over the second substrate emit light,reference numerals 1416, 1417, and 1418 become magenta light emittingregions. In the case of making only the yellow light emitting region1412 over the second substrate emit light, reference numerals 1419,1420, and 1421 become yellow light emitting regions.

Note that the example of forming the cyan, magenta, and yellow organiclight emitting elements is shown in this embodiment; however, thepresent invention is not limited thereto. A one colored organic lightemitting element or two colored organic light emitting elements selectedfrom cyan, magenta, and yellow may be formed. Further, the colors oforganic light emitting elements to be formed are not particularlylimited to cyan, magenta, and yellow, which are complementary colors ofred, green, and blue. Colors other than red, green, blue, cyan, magenta,and yellow may be employed so long as they can widen the range of colorsto be displayed. That is, any colored organic light emitting element maybe employed so long as the organic light emitting element emits lightwith a color having a chromaticity coordinate outside of the range of atriangle of red, green, and blue chromaticity coordinates.

Further, in this embodiment, the case where the red, green, and blueorganic light emitting elements are provided over the first substrate,the cyan, magenta, and yellow organic light emitting elements areprovided over the second substrate, and a display screen is providedover the first substrate, is described; however, the present inventionis not limited thereto.

The positions of the organic light emitting elements provided over thefirst substrate and the organic light emitting elements provided overthe second substrate, may be counterchanged. Specifically, the cyan,magenta, and yellow organic light emitting elements may be provided overthe first substrate whereas the red, green, and blue organic lightemitting elements may be provided over the second substrate.

Further, display screens may be provided over both of the first andsecond substrates. In this case, dual emission type organic lightemitting elements may be provided over both of the first and secondsubstrates. Specifically, first electrodes and second electrodes of theorganic light emitting elements provided over both of the first andsecond substrates may be formed using transparent conductive films.

Embodiment 2

The display device in which the organic light emitting elements providedover the first and second substrates are sealed with the first andsecond substrates such that the surfaces of the first and secondsubstrates over which the organic light emitting elements are providedface each other, is described in each of the above described EmbodimentModes. In this embodiment, a display device having a structure in whichorganic light emitting elements provided over first and secondsubstrates are sealed with a third substrate, will be described withreference to FIGS. 21A and 21B.

In this embodiment, the arrangements of organic light emitting elementsprovided over a first substrate and a second substrate are the same asthe first structure of the present invention as well as Embodiment Mode1, that is, in the case A of the present invention, wherein red, green,and blue organic light emitting elements are provided over a firstsubstrate and a white organic light emitting element is provided over asecond substrate; however, the present invention is not limited to thiscase. A combination of organic light emitting elements provided overeach of the first and second substrates may be any case of the first tofourth structures of the present invention.

In FIG. 21A, reference numeral 1500 indicates a first substrate; 1501, asecond substrate; and 1530, a third substrate. As the first and secondsubstrates 1500 and 1501, light transmitting substrates such as a glasssubstrate and a plastic substrate are used.

Over the first substrate 1500, a red organic light emitting element1521, a green organic light emitting element 1522, and a blue organiclight emitting element 1523 are provided. Over the second substrate1501, a white organic light emitting element 1520 is provided.

The red organic light emitting element 1521 includes a first electrode1510, a second electrode 1508, and a layer 1509 containing an organiccompound sandwiched between the first electrode 1510 and the secondelectrode 1508. The green organic light emitting element 1522 includes afirst electrode 1513, a second electrode 1511, and a layer 1512containing an organic compound sandwiched between the first electrode1513 and the second electrode 1511. The blue organic light emittingelement 1523 includes a first electrode 1516, a second electrode 1514,and a layer 1515 containing an organic compound sandwiched between thefirst electrode 1516 and the second electrode 1514.

The white organic light emitting element 1520 includes a first electrode1505, a second electrode 1507, and a layer 1506 containing an organiccompound sandwiched between the first electrode 1505 and the secondelectrode 1507.

As shown in FIG. 21A, the first and second substrates are attached toeach other such that a surface of the first substrate over which theorganic light emitting elements 1521, 1522, and 1523 are provided facesa surface of the second substrate, which is opposite to the othersurface of the second substrate over which the organic light emittingelement 1520 is provided.

Further, the second substrate is attached to a third substrate such thatthe surface of the second substrate over which the organic lightemitting element 1520 is provided faces a surface of the thirdsubstrate.

The second substrate serves as a counter substrate with respect to thefirst substrate whereas the third substrate serves as a countersubstrate with respect to the second substrate.

The organic light emitting elements 1521, 1522, and 1523 provided overthe first substrate have a dual emission structure, in which the organiclight emitting elements emit light toward the both sides of the firstsubstrate 1500. Accordingly, the first electrodes 1510, 1513, and 1516and the second electrodes 1508, 1511, and 1514 of the organic lightemitting elements 1521, 1522, and 1523 provided over the first substrateare formed using transparent conducive films.

The organic light emitting element 1520 provided over the secondsubstrate has a bottom emission type structure, in which the organiclight emitting element emits light toward the surface of the secondsubstrate 1501 opposite to the other surface of the second substrateover which the organic light emitting element 1520 is provided, i.e.,toward the first substrate. Accordingly, the first electrode 1505 of theorganic light emitting element 1520 is formed using a transparentconductive film whereas the second electrode 1507 thereof is formedusing an electrode having a function of reflecting light. As theelectrode having a function of reflecting light, the materials describedin Embodiment Mode 1 may be used.

Further, arrows of FIG. 21A indicate the directions of light emittedfrom the respective organic light emitting elements.

According to the above described structure, the organic light emittingelements 1521, 1522, and 1523 emit light toward the both sides of thefirst substrate 1500 whereas the white organic light emitting element1520 emits light toward the surface of the second substrate 1501opposite to the other surface of the second substrate over which theorganic light emitting element 1520 is provided. Light emitted towardthe second substrate 1501 from the organic light emitting elements 1521,1522, and 1523 is reflected by the second electrode 1507 (the electrodehaving a function of reflecting light) of the white organic lightemitting element 1520 provided over the second substrate 1501, and thereflected light travels toward the first substrate 1500. A displayscreen is provided over the first substrate 1500, and an image whosebrightness is controlled by the white organic light emitting element1520 is displayed on the display screen.

In the display device having the structure in which the organic lightemitting elements are sealed with the three substrates, the positions ofthe organic light emitting elements provided over the first substrateand the organic light emitting elements provided over the secondsubstrate, may be counterchanged. Further, display screens may beprovided over both of the first and second substrates.

FIG. 21B shows an example in which positions of the organic lightemitting elements provided over the first substrate and the organiclight emitting elements provided over the second substrate arecounterchanged. In FIG. 21B, the same portions as those of FIG. 21A aredenoted by same reference numerals.

The first substrate 1500 and the second substrate 1501 are attached toeach other such that the surface of the second substrate 1501 over whichthe organic light emitting element 1520 is provided faces the surface ofthe first substrate 1500 opposite to the other surface of the firstsubstrate over which the organic light emitting elements 1521, 1522, and1523 are provided. Further, the first substrate 1500 and the thirdsubstrate are attached to each other such that the surface of the firstsubstrate over which the organic light emitting elements 1521, 1522, and1523 are provided faces the surface of the third substrate.

Differing from FIG. 21A, in FIG. 21B, the positions of the firstsubstrate 1500 and the second substrate 1501 are counterchanged, thesecond electrodes 1508, 1511, and 1514 of the organic light emittingelements 1521, 1522, and 153 provided over the first substrate areformed using electrodes having a function of reflecting light, and thesecond electrode 1507 of the organic light emitting element 1520provided over the second substrate 1501 is formed using a transparentconductive film.

According to this structure, the organic light emitting elements 1521,1522, and 1523 provided over the first substrate 1500 emit light towardthe direction opposite to the surface of the first substrate 1500 overwhich the organic light emitting elements 1521, 1522, and 1523 areprovided while the organic light emitting element 1520 provided over thesecond substrate 1501 emits light toward the both surfaces of the secondsubstrate. Light emitted toward the first substrate 1500 from the whiteorganic light emitting element 1520 is reflected by the secondelectrodes (electrodes having a function of reflecting light) of theorganic light emitting elements 1521, 1522, and 1523 provided over thefirst substrate, and then the reflected light travels toward the secondsubstrate 1501. In this case, a display screen is provided over thesecond substrate, and an image whose brightness is controlled by thewhite organic light emitting element 1520 is displayed on the displayscreen.

Moreover, an example of a display device having organic light emittingelements sealed with three substrates in which display screens areprovided over both surfaces of substrates, will be described withreference to FIG. 22.

In FIG. 22, the same reference numerals are used in the same portions asthose of FIG. 21A. Differing from FIG. 21A, in FIG. 22, the secondelectrode 1507 of the organic light emitting element 1520 provided overthe second substrate 1501 is formed using a transparent conductive film.

According to this structure, since the first and second electrodes ofthe organic light emitting elements 1521, 1522, and 1523 provided overthe first substrate 1500 and the organic light emitting element 1520provided over the second substrate 1501 are formed using transparentconductive films, the organic light emitting elements 1521, 1522, and1523 provided over the first substrate and the organic light emittingelement 1520 provided over the second substrate have a dual emissionstructure. Thus, light is emitted from both of the first substrate 1500and the third substrate 1530 as shown in FIG. 22, and hence, the displayscreens can be provided over the both of the first and third substrates.

Note that, an image recognized on the display screen formed over thefirst substrate is a mirrored image of an image recognized on thedisplay screen formed over the third substrate. Further, since the firstand second substrates are the light transmitting substrates, the displayscreens of the first and second substrates are formed while a viewer cansee the view beyond the first and third substrates.

Further, by providing polarizing plates over the first and thirdsubstrates, it is possible to prevent a viewer from seeing the viewbeyond the first and third substrates on the display screens formed overthe first and third substrates.

Furthermore, a display screen may be provided only over the thirdsubstrate. In this case, the organic light emitting elements providedover the first substrate may have a top emission structure, the organiclight emitting element provided over the second substrate may have adual emission structure, and light transmitting substrates may be usedas the second and third substrates. That is, the second electrodes ofthe organic light emitting elements provided over the first substratemay be formed using a transparent conductive film and the first andsecond electrodes of the organic light emitting element provided overthe second substrate may be formed using transparent conductive films.

FIG. 21A shows the structure in which the display screen is providedonly over the first substrate 1500. Alternatively, in a case where thedisplay screen is provided only over the third substrate 1530, thesecond electrodes 1508, 1511, and 1514 of the organic light emittingelements 1521, 1522, and 1523 provided over the first substrate 1500 maybe formed using a transparent conductive film, and the first electrode1505 and the second electrode 1507 of the organic light emitting element1520 provided over the second substrate 1501 may be formed usingtransparent conductive films.

Embodiment 3

In this embodiment, an example of a more specific cross sectionalstructure of the display device shown in FIG. 1 will be described withreference to FIG. 23. FIG. 23 is a cross sectional view along a lineA-A′ of the display device shown in FIG. 1. Note that, FIG. 23 shows amore specific cross sectional structure of the display device shown inFIG. 1 in a case where the display device has the cross sectionalstructure shown in FIG. 3A. Specifically, an example of a crosssectional structure of the display device of FIG. 1 in a case where afirst substrate over which red, green, and blue organic light emittingelements are provided is overlapped with a second substrate over which awhite organic light emitting element is provided and a display screen isprovided over the first substrate, will be shown here. Note that, inFIG. 23, a cross sectional portion shows a cross sectional view of onepixel.

First, TFTs 1620R, 1620G, and 1620B provided in a pixel portion, aperipheral driver circuit TFT 1650, an insulating film 1612, and aprotection film 1613 are formed over a first substrate 1601. Leadingwirings 1614 and 1615, and a connection terminal 1616 are formed at thesame time of forming these TFTs. Further, the TFT 1620R is a thin filmtransistor for driving a red organic light emitting element; the TFT1620G, a thin film transistor for driving a green organic light emittingelement; and the TFT 1620B, a thin film transistor for driving a blueorganic light emitting element.

Next, first electrodes 1641 serving as anodes (or cathodes) of organiclight emitting elements 1621R, 1621G, and 1621B are formed, and aninsulator (a partition wall) 1628 covering the edges of the firstelectrodes are formed. Subsequently, layers containing organic compoundsand second electrodes are formed to form the organic light emittingelements 1621R, 1621G, and 1621B. Note that the organic light emittingelement 1621R is a red organic light emitting element; 1621G, a greenorganic light emitting element; and 1621B, a blue organic light emittingelement. The first and second electrodes of the respective organic lightemitting elements are formed using transparent conductive films. Byforming the first and second electrodes of the respective organic lightemitting elements by using the transparent conductive films, the organiclight emitting elements have a dual emission structure.

A protection film 1643 is formed over the organic light emittingelements 1621R, 1621, and 1621B.

Further, the layer containing the organic compound included in theorganic light emitting element 1621R contains a red light emittingmaterial, the layer containing the organic compound included in theorganic light emitting element 1621G contains a green light emittingelement, and the layer containing the organic compound included in theorganic light emitting element 1621B contains a blue light emittingmaterial.

A TFT 1610W, a peripheral driver circuit TFT 1651, an insulating film1602, and a protection film 1603 are also formed over a second substrate1606. Leading wirings 1624 and 1625, and a connection terminal 1636 areformed at the same time of forming the TFT 1610W. Note that the TFT1610W is a thin film transistor for driving a white organic lightemitting element.

Next, a first electrode 1640 serving as an anode (or a cathode) of theorganic light emitting element 1611W is formed, and an insulator (apartition wall) 1608 covering the edge of the first electrode is formed.Subsequently, a layer containing an organic compound and a secondelectrode are formed to achieve the organic light emitting element1611W. Note that, the organic light emitting element 1611W is a whiteorganic light emitting element, the first electrode of the organic lightemitting element 1611W is formed using an electrode having a function ofreflecting light, and the second electrode is formed using a transparentconductive film.

A protection film 1642 is formed over the organic light emitting element1611W. Further, the layer containing the organic compound included inthe organic light emitting element 1611W contains a white light emittingmaterial.

Next, the first substrate 1601 and the second substrate 1606 areattached to each other with a sealing material 1605 and a filler 1607.As the filler 1607, a transparent material is used. As shown in FIG. 23,the first and second substrates are attached to each other such that asurface of the first substrate over which the organic light emittingelements 1621R, 1621Q and 1621B are formed faces a surface of the secondsubstrate over which the organic light emitting element 1611W is formedwhile the organic light emitting elements 1621R, 1621G, and 1621B formedover the first substrate are overlapped with the organic light emittingelement 1611W formed over the second substrate. Thus, a display devicefor full color display whose brightness can be controlled by the whiteorganic light emitting element, is completed.

Then, FPCs 1618 and 1638 are attached to the connection terminals 1616and 1636 by anisotropic conductive films 1619 and 1639.

In the display device as shown in FIG. 23, the organic light emittingelements 1621R, 1621G, and 1621B formed over the first substrate emitlight toward the both surfaces of the first substrate. Light emittedtoward the second substrate from the organic light emitting elements1621R, 1621G, and 1621B is reflected by the first electrode (theelectrode having a function of reflecting light) of the white organiclight emitting element 1611W formed over the second substrate, and thereflected light travels toward the first substrate. Further, the whiteorganic light emitting element 1611W formed over the second substrateemits light toward the first substrate. Accordingly, a viewer canrecognize a display generated by light emitted from the respectiveorganic light emitting elements, which passes through the firstsubstrate. In this case, a display screen is provided over the firstsubstrate. Further, in FIG. 23, arrows indicate the directions of lightemitted from the respective organic light emitting elements.

In the case of the structure shown in FIG. 23, only white light emittedfrom the organic light emitting element 1611W formed over the secondsubstrate passes through the first substrate at a portion in which theorganic light emitting elements 1621R, 1621G, and 1621B are not formedover the first substrate, and for example, at a portion where the TFTs1620R, 1620G, and 1620B are formed. Accordingly, the white light issometimes seen at the portion. In this case, the insulator (partitionwall) 1628 covering the edges of the first electrodes formed over thefirst substrate is colored and this colored partition wall 1628 mayserve as a black matrix. In order to color the partition wall 1628, thepartition wall may be formed using a resin material in which a fineparticle pigment is dispersed.

Further, a structure in which the positions of the first substrate andthe second substrate of the structure of FIG. 23 are counterchanged,will be described with reference to FIG. 24. A connection portionbetween a peripheral driver circuit and an FPC is not shown in FIG. 24,and FIG. 24 shows a cross sectional view of one pixel in a pixelportion. In FIG. 24, the same portions as those of FIG. 23 are denotedby the same reference numerals.

The display device shown in FIG. 24 may be manufactured in the samemanner as the display device shown in FIG. 23. However, in the case ofthe display device shown in FIG. 24, the first electrodes of the organiclight emitting elements 1621R, 1621G, and 1621B formed over the firstsubstrate are formed using electrodes having a function of reflectinglight while the second electrodes are formed using transparentconductive films. Further, the first and second electrodes of the whiteorganic light emitting element 1611W formed over the second substrateare formed using transparent conductive films.

In the display device shown in FIG. 24, the organic light emittingelements 1621R, 1621G, and 1621B formed over the first substrate emitlight toward a surface of the first substrate over which the organiclight emitting elements 1621R, 1621G, and 1621B are formed. That is,light generated in the organic light emitting elements 1621R, 1621G, and1621B is emitted toward the second substrate. The white organic lightemitting element 1611W formed over the second substrate emits lighttoward the both surfaces of the second substrate. Light emitted towardthe first substrate from the organic light emitting element 1611W isreflected by the first electrodes (electrodes having a function ofreflecting light) of the organic light emitting elements 1621R, 1621G,and 1621B formed over the first substrate, and the reflected lighttravels toward the second substrate. Thus, the display device shown inFIG. 24 has a structure in which a viewer can recognize a displaygenerated by light emitted from the respective organic light emittingelements, which passes through the second substrate. That is, a displayscreen is provided over the second substrate. Note that, in FIG. 24,arrows indicate the directions of light emitted from the respectiveorganic light emitting elements.

In the display device shown in FIG. 24, the organic light emittingelement 1611W is formed at a portion through which light generated fromthe organic light emitting elements 1621R, 1621G, and 1621B passes.Accordingly, the partition wall 1608 does not exist in the portionthrough which light generated from the organic light emitting elements1621R, 1621G, and 1621B passes, and therefore, light generated from theorganic light emitting elements 1621R, 1621G, and 1621B easily passesthrough the second substrate 1606.

In addition, when the interlayer insulating film 1602 and the protectionfilm 1603 are formed using a material having high transmittance withrespect to light emitted from the organic light emitting elements 1621R,1621G, and 1621B, light emitted from the organic light emitting elementscan easily passes through the interlayer insulating film and theprotection film. Also, in order to further increase the transmittance, apart of the interlayer insulating film 1602 or the protection film 1603may be selectively eliminated at a portion through which light emittedfrom the organic light emitting elements 1621R, 1621G, and 1621B passes.

In FIG. 23 and FIG. 24, the TFTs for driving the organic light emittingelements have a top gate structure. However, the structure of the TFTsis not limited to the top gate structure, and a known TFT structure suchas a bottom gate structure can be used.

Further, the display screen is formed only over the one surface of thedisplay device in each of FIG. 23 and FIG. 24. Alternatively, displayscreens can be provided over the both surfaces of each display device(i.e., the display screens are provided over the first and secondsubstrates). In this case, the first and second electrodes of theorganic light emitting elements 1621R, 1621G, and 1621B formed over thefirst substrate and the first and second electrodes of the organic lightemitting element 1611W formed over the second substrate may be formedusing transparent conductive films.

The example of Embodiment Mode 1 in which the white organic lightemitting element is formed over the second substrate, is employed inthis embodiment. Furthermore, this embodiment can be applied to otherEmbodiment Modes and Embodiments.

Embodiment 4

A structural example in which a viewer cannot see the view beyond thefirst and second substrates in a case where images are displayed overboth surfaces of a display device, will be described in this embodimentwith reference to FIGS. 31A and 31B.

FIGS. 31A and 31B are cross sectional views of display devices, whereinimages are displayed on both surfaces of each display device. Arrowsindicate the directions of light emission. In FIG. 31A, referencenumeral 4000 is a first substrate and reference numeral 4001 is a secondsubstrate. A dual emission type organic light emitting elements areprovided over one surface of each of the first and second substrates4000 and 4001 though not shown in the drawings. The first and secondsubstrates 4000 and 4001 are attached to each other such that theorganic light emitting elements provided over the first and secondsubstrates are face each other and are sealed with a sealing material4002 and a sealing material 4003. Thus, a panel is obtained. Further,the first and second substrates are sandwiched between a firstpolarizing plate 4004 and a second polarizing plate 4005 such thatpolarizing directions of light are orthogonal to each other. When thefirst and second polarizing plates 4004 and 4005 are arranged such thatthe polarizing directions of light are orthogonal to each other, outsidelight can be shielded. In addition, light emitted from the panel onlypasses through one polarizing plate so as to perform a display.Accordingly, by providing the first polarizing plate 4004 and the secondpolarizing plate 4005 in such a manner, since a portion other than aportion displaying an image becomes black, a viewer cannot see the viewbeyond the first and second substrates when the viewer sees the bothdisplay screens provided over the first and second substrates, therebypreventing the display screen from being difficult to be recognized.

Further, λ/4 wavelength plates may be provided between the firstsubstrate 4000 and the first polarizing plate 4004 and between thesecond substrate 4001 and the second polarizing plate 4005. An exampleof this structure will be shown in FIG. 31B. In FIG. 31B, the sameportions as those of FIG. 31A are denoted by the same referencenumerals. Differing from FIG. 31A, in FIG. 31B, a first λ/4 wavelengthplate 4006 is provided between the first substrate 4000 and the firstpolarizing plate 4004 and a second λ/4 wavelength plate 4007 is providedbetween the second substrate 4001 and the second polarizing plate 4005.When the first and second λ/4 wavelength plates are provided between thefirst substrate and the first polarizing plate and between the secondsubstrate and the second polarizing plate, it is possible to prevent aviewer from seeing the view beyond the first and second substrates onthe display screens. In addition, reduction in contrast caused byreflection of outside light at the panel can be inhibited.

In FIGS. 31A and 31B, there are a space between the first substrate andthe first polarizing plate, a space between the first substrate and thefirst λ/4 wavelength plate, a space between the first λ/4 wavelengthplate and the first polarizing plate, a space between the secondsubstrate and the second polarizing plate, a space between the secondsubstrate and the second λ/4 wavelength plate, and a space between thesecond λ/4 wavelength plate and the second polarizing plate. However,this embodiment is not limited to the structure, and they may beprovided to be in contact with one another.

Furthermore, in FIG. 31B, a first λ/2 wavelength plate may be providedbetween the first polarizing plate 4004 and the first λ/4 wavelengthplate 4006 and a second λ/2 wavelength plate may be provided between thefirst polarizing plate 4005 and the second λ/4 wavelength plate 4007.

The examples of preventing a viewer from seeing the view beyond thefirst and second substrates on the display screens is described in thisembodiment. In a case where an image is displayed on one display screen,it is not necessary to prevent a viewer from seeing the view beyond thefirst and second substrates, and therefore, a polarizing plate is notrequired. However, in this case, it is necessary to prevent reduction incontrast caused by reflection of outside light at the panel.Accordingly, in the case where an image is displayed on one displayscreen, reduction in contrast caused by reflection of outside light atthe panel can be prevented by providing a λ/4 wavelength plate betweenthe display screen and the viewer or a λ/4 wavelength plate and a λ/2wavelength plate between the display screen and the viewer.

Note that the present embodiment can be implemented in the abovedescribed display device having any structure, and can be applied to allof Embodiment Modes 1 through 7 and Embodiments 1 through 4.

Embodiment 5

By incorporating display devices according to the present invention,various kinds of electronic appliances can be manufactured. As theelectronic appliances, a camera such as a video camera and a digitalcamera; a goggle type display (a head mounted display); a navigationsystem; a sound reproduction device (such as a car audio and an audiocomponent system); a laptop personal computer; a game machine; aportable information terminal (such as a mobile computer, a cellulartelephone, a portable game machine, and an electronic book); a picturereproducer provided with a recording medium (typically, a device whichcan play the recording medium such as a digital versatile disc (DVD) anddisplay images thereof); and the like can be given. Specific examples ofthese electronic appliances are shown in FIGS. 25A to 25H and FIG. 26.

FIG. 25A is a television including a housing 2001, a supporting base2002, a display portion 2003, speaker portions 2004, a video inputterminal 2005, and the like. The present invention can be applied to thedisplay portion 2003. Further, the television also includes allinformation displaying apparatuses for a computer, a TV broadcasting,advertisement, and the like.

FIG. 25B is a digital camera including a main body 2101, a displayportion 2102, an image receiving portion 2103, operation keys 2104, anexternal connection port 2105, a shutter 2106, and the like. The presentinvention can be applied to the display portion 2102.

FIG. 25C is a laptop personal computer including a main body 2201, ahousing 2202, a display portion 2203, a keyboard 2204, an externalconnection port 2205, a pointing mouse 2206, and the like. The presentinvention can be applied to the display portion 2203.

FIG. 25D is a mobile computer including a main body 2301, a displayportion 2302, a switch 2303, operation keys 2304, an infrared port 2305,and the like. The present invention can be applied to the displayportion 2302.

FIG. 25E is a portable picture reproducer equipped with a recordingmedium (specifically, a DVD reproducer), including a main body 2401, ahousing 2402, a display portion A 2403, a display portion B 2404, arecording medium (e.g., a DVD or the like) reading portion 2405,operation keys 2406, speakers 2407, and the like. The display portion A2403 mainly displays image information whereas the display portion Bmainly displays character information. The present invention can beapplied to the display portion A 2403 and the display portion B 2404.Further, the picture reproducer equipped with a recording mediumincludes a home-use game machine and the like.

FIG. 25F is a game machine including a main body 2501, a display portion2505, operation switches 2504, and the like.

FIG. 25G is a video camera including a main body 2601, a display portion2602, a housing 2603, an external connection port 2604, a remote controlreceiver 2605, an image receiving portion 2606, a buttery 2607, an audioinput portion 2608, operation keys 2609, eyepiece portions 2610, and thelike. The present invention can be applied to the display portion 2602.

FIG. 25H is a cellular phone including a main body 2701, a housing 2702,a display portion 2703, an audio input portion 2704, an audio outputportion 2705, operation keys 2706, an external connection port 2707, anantenna, 2708 and the like. The present invention can be applied to thedisplay portion 2703.

FIG. 26 is an audio player including a main body 2801, a half-mirrorpanel 2802, operation keys 2803, earphones 2804, and the like. A displayportion is provided in a part of the half-mirror panel 2802. When animage is not displayed on the display portion, the half-mirror panel islike a mirror. A display device according to the present invention canbe applied to the display device provided in a part of the half-mirrorpanel 2802.

The digital camera, the laptop personal computer, the gate machine, thevideo camera, the cellular phone, and the like among the above mentionedelectronic appliances can be freely carried, and therefore, they can beused in the open air and in doors. Since brightness in the open air isdifferent from brightness in doors, optimum brightness (which is easilyvisible) of a display screen is differed between a case of using suchelectronic appliances in the open air and a case of using them in doors.When a panel is formed by attaching a substrate over which red, green,and blue organic light emitting elements are provided to anothersubstrate over which a white organic light emitting element is provided,and a light sensor for detecting surrounding brightness is provided tochange luminance of the white organic light emitting element inaccordance with the surrounding brightness detected by the light sensor,brightness of a display screen can be controlled in accordance withchanges in brightness around an electronic appliance.

As set forth above, the display devices obtained according to thepresent invention can be used as display portions for various electronicappliances. Note that the light emitting device manufactured using anystructures described in Embodiment Modes 1 through 7 and Embodiments 1through 4 may be used for the electronic appliances of this embodiment.

This application is based on Japanese Patent Application Serial No.2005-121746 filed in Japan Patent Office on Apr. 19, in 2005, the entirecontents of which are hereby incorporated by reference.

1. A display device comprising: a first substrate; a second substrate;an organic light emitting element provided over a surface of the firstsubstrate; and an organic light emitting element provided over a thesecond substrate, wherein the first substrate faces the secondsubstrate, wherein each of the organic light emitting elements includesa first electrode, a second electrode, and a layer containing an organiccompound sandwiched between the first electrode and the secondelectrode, wherein the first and second electrodes of at least one ofthe organic light emitting elements provided over the first and secondsubstrates, comprise a transparent conductive film, and wherein a lightemitting region of the organic light emitting element provided over thefirst substrate is at least partly overlapped with a light emittingregion of the organic light emitting element provided over the secondsubstrate.
 2. A display device comprising: a first substrate having afirst surface and a second surface; a second substrate having a firstsurface and a second surface; an organic light emitting element providedover the first surface of the first substrate; and an organic lightemitting element provided over the first surface of the secondsubstrate, wherein the first and second substrates are placed such thatthe first surface of the first substrate faces the first surface of thesecond substrate, wherein each of the organic light emitting elementsincludes a first electrode, a second electrode, and a layer containingan organic compound sandwiched between the first electrode and thesecond electrode, wherein the organic light emitting element providedover the first substrate emits light toward both surfaces of the firstsubstrate, wherein the organic light emitting element provided over thesecond substrate emits light toward both surfaces of the secondsubstrate, wherein the first and second substrates are lighttransmitting substrates, and wherein a light emitting region of theorganic light emitting element provided over the first substrate is atleast partly overlapped with a light emitting region of the organiclight emitting element provided over the second substrate.
 3. A displaydevice comprising: a first substrate having a first surface and a secondsurface; a second substrate having a first surface and a second surface;an organic light emitting element provided over the first surface of thefirst substrate; and an organic light emitting element provided over thefirst surface of the second substrate, wherein each of the organic lightemitting elements includes a first electrode, a second electrode, and alayer containing an organic compound sandwiched between the firstelectrode and the second electrode, wherein the organic light emittingelement provided over the first substrate emits light toward bothsurfaces of the first substrate, wherein the organic light emittingelement provided over the second substrate emits light toward the firstsurface of the second substrate, wherein the first and second substratesare placed such that the first surface of the first substrate faces thefirst surface of the second substrate, wherein the first substrate is alight transmitting substrate, and wherein a light emitting region of theorganic light emitting element provided over the first substrate is atleast partly overlapped with a light emitting region of the organiclight emitting element provided over the second substrate.
 4. A displaydevice comprising: a first substrate having a first surface and a secondsurface; a second substrate having a first surface and a second surface;a third substrate having a first surface and a second surface; anorganic light emitting element provided over the first surface of thefirst substrate; and an organic light emitting element provided over thefirst surface of the second substrate, wherein each of the organic lightemitting elements includes a first electrode, a second electrode, and alayer containing an organic compound sandwiched between the firstelectrode and the second electrode, wherein the organic light emittingelement provided over the first substrate emits light toward bothsurfaces of the first substrate, wherein the organic light emittingelement provided over the second substrate emits light toward bothsurfaces of the second substrate, wherein the first and secondsubstrates are placed such that the first surface of the first substratefaces the second surface of the second substrate, wherein the second andthird substrates are placed such that the first surface of the secondsubstrate faces the third substrate, wherein the first, second, andthird substrates are light transmitting substrates, and wherein a lightemitting region of the organic light emitting element provided over thefirst substrate is at least partly overlapped with a light emittingregion of the organic light emitting element provided over the secondsubstrate.
 5. A display device comprising: a first substrate a firstsurface and a second surface; a second substrate a first surface and asecond surface; a third substrate a first surface and a second surface;an organic light emitting element provided over the first surface of thefirst substrate; and an organic light emitting element provided over thefirst surface of the second substrate, wherein each of the organic lightemitting elements includes a first electrode, a second electrode, and alayer containing an organic compound sandwiched between the firstelectrode and the second electrode, wherein the organic light emittingelement provided over the first substrate emits light toward the firstsurface of the first substrate, wherein the organic light emittingelement provided over the second substrate emits light toward bothsurfaces of the second substrate, wherein the first and secondsubstrates are placed such that the first surface of the first substratefaces the second surface of the second substrate, wherein the second andthird substrates are placed such that the first surface of the secondsubstrate faces the third substrate, wherein the second and thirdsubstrates are light transmitting substrates, and wherein a lightemitting region of the organic light emitting element provided over thefirst substrate is at least partly overlapped with a light emittingregion of the organic light emitting element provided over the secondsubstrate.
 6. A display device comprising: a first substrate a firstsurface and a second surface; a second substrate a first surface and asecond surface; a third substrate a first surface and a second surface;an organic light emitting element provided over the first surface of thefirst substrate; and an organic light emitting element provided over thefirst surface of the second substrate, wherein each of the organic lightemitting elements includes a first electrode, a second electrode, and alayer containing an organic compound sandwiched between the firstelectrode and the second electrode, wherein the organic light emittingelement provided over the first substrate emits light toward bothsurfaces of the first substrate, wherein the organic light emittingelement provided over the second substrate emits light toward the secondsurface of the second substrate, wherein the first and second substratesare placed such that the first surface of the first substrate faces thesecond surface of the second substrate, wherein the second and thirdsubstrates are placed such that the first surface of the secondsubstrate faces the third substrate, wherein the first substrate is alight transmitting substrate, and wherein a light emitting region of theorganic light emitting element provided over the first substrate is atleast partly overlapped with a light emitting region of the organiclight emitting element provided over the second substrate.
 7. Thedisplay device according to claim 1, wherein the first and secondsubstrates are sandwiched between a first polarizing plate and a secondpolarizing plate.
 8. The display device according to claim 1, wherein afirst organic light emitting element is provided over the firstsubstrate, wherein a second organic light emitting element, a thirdorganic light emitting element, and a fourth organic light emittingelement are provided over the second substrate, and wherein the first tofourth organic light emitting elements are included in one pixel.
 9. Thedisplay device according to claim 1, wherein a first organic lightemitting element is provided over the second substrate, wherein a secondorganic light emitting element, a third organic light emitting element,and a fourth organic light emitting element are provided over the firstsubstrate, and wherein the first to fourth organic light emittingelements are included in one pixel.
 10. The display device according toclaim 1, wherein a first organic light emitting element and a secondorganic light emitting element are provided over the first substrate,wherein a third organic light emitting element and a fourth organiclight emitting element are provided over the second substrate, wherein alight emitting region of the first organic light emitting element isoverlapped with a light emitting region of the third organic lightemitting element, wherein a light emitting region of the second organiclight emitting element is overlapped with a light emitting region of thefourth organic light emitting element, and wherein the first to fourthorganic light emitting elements are included in one pixel.
 11. Thedisplay device according to claim 1, wherein a first organic lightemitting element and a second organic light emitting element areprovided over the first substrate, wherein a third organic lightemitting element and a fourth organic light emitting element areprovided over the second substrate, wherein a light emitting region ofthe first organic light emitting element is overlapped with a lightemitting region of the third organic light emitting element and a lightemitting region of the fourth organic light emitting element, wherein alight emitting region of the second organic light emitting element isoverlapped with the light emitting region of the third organic lightemitting element and the light emitting region of the fourth organiclight emitting element, and wherein the first to fourth organic lightemitting elements are included in one pixel.
 12. The display deviceaccording to claim 1, wherein a first organic light emitting element, asecond organic light emitting element, and a third organic lightemitting element are provided over the first substrate, wherein a fourthorganic light emitting element, a fifth organic light emitting element,and a sixth organic light emitting element are provided over the secondsubstrate, wherein a light emitting region of the first organic lightemitting element and a light emitting region of the fourth organic lightemitting element are overlapped with each other, wherein a lightemitting region of the second organic light emitting element and a lightemitting region of the fifth organic light emitting element areoverlapped with each other, wherein a light emitting region of the thirdorganic light emitting element and a light emitting region of the sixthorganic light emitting element are overlapped with each other, andwherein the first to sixth organic light emitting elements are includedin one pixel.
 13. The display device according to claim 1, wherein afirst organic light emitting element, a second organic light emittingelement, and a third organic light emitting element are provided overthe first substrate, wherein a fourth organic light emitting element, afifth organic light emitting element, and a sixth organic light emittingelement are provided over the second substrate, wherein a light emittingregion of the first organic light emitting element is overlapped withlight emitting regions of the fourth to sixth organic light emittingelements, wherein a light emitting region of the second organic lightemitting element is overlapped with the light emitting regions of thefourth to sixth organic light emitting elements, wherein a lightemitting region of the third organic light emitting element isoverlapped with the light emitting regions of the fourth to sixthorganic light emitting elements, and wherein the first to sixth organiclight emitting elements are included in one pixel.
 14. The displaydevice according to claim 1, wherein a red organic light emittingelement, a green organic light emitting element, and a blue organiclight emitting element are provided over the second substrate, wherein awhite organic light emitting element is provided over the firstsubstrate, and wherein a light emitting region of the white organiclight emitting element is overlapped with light emitting regions of thered, green, and blue organic light emitting elements.
 15. The displaydevice according to claim 1, wherein a red organic light emittingelement, a green organic light emitting element, and a blue organiclight emitting element are provided over the first substrate, andwherein a first white organic light emitting element facing the redorganic light emitting element, a second white organic light emittingelement facing the green organic light emitting element, and a thirdwhite organic light emitting element facing the blue organic lightemitting element are provided over the second substrate.
 16. The displaydevice according to claim 1, wherein a red organic light emittingelement, a green organic light emitting element, and a blue organiclight emitting element are provided over the second substrate, andwherein a first white organic light emitting element facing the redorganic light emitting element, a second white organic light emittingelement facing the green organic light emitting element, and a thirdwhite organic light emitting element facing the blue organic lightemitting element are provided over the first substrate.
 17. The displaydevice according to claim 1, wherein a red organic light emittingelement and either a green organic light emitting element or a whiteorganic light emitting element are provided over the first substrate,wherein a blue organic light emitting element and either the greenorganic light emitting element or the white organic light emittingelement are provided over the second substrate, wherein a light emittingregion of the red organic light emitting element is overlapped with alight emitting region of the blue organic light emitting element, andwherein a light emitting region of either the green organic lightemitting element or the white organic light emitting element isoverlapped with a light emitting region of either the green organiclight emitting element or the white organic light emitting element. 18.The display device according to claim 1, wherein a red organic lightemitting element and either a green organic light emitting element or awhite organic light emitting element are provided over the firstsubstrate, wherein a blue organic light emitting element and either thegreen organic light emitting element or the white organic light emittingelement are provided over the second substrate, wherein a light emittingregion of the red organic light emitting element is overlapped with alight emitting region of either the green organic light emitting elementor the white organic light emitting element, and wherein a lightemitting region of either the green organic light emitting element orthe white organic light emitting element is overlapped with a lightemitting region of the blue organic light emitting element.
 19. Thedisplay device according to claim 1, wherein a red organic lightemitting element and either a green organic light emitting element or awhite organic light emitting element are provided over the firstsubstrate, wherein a blue organic light emitting element and either agreen organic light emitting element or a white organic light emittingelement are provided over the second substrate, wherein a light emittingregion of the red organic light emitting element is overlapped with alight emitting region of the blue organic light emitting element and alight emitting region of either the green organic light emitting elementor the white organic light emitting element, and wherein a lightemitting region of either the green organic light emitting element orthe white organic light emitting element is overlapped with the lightemitting region of the blue organic light emitting element and a lightemitting region of either the green organic light emitting element orthe white organic light emitting element.
 20. The display deviceaccording to claim 1, wherein a blue organic light emitting element andeither a green organic light emitting element or a white organic lightemitting element are provided over the first substrate, wherein a redorganic light emitting element and either a green organic light emittingelement or a white organic light emitting element are provided over thesecond substrate, wherein a light emitting region of the blue organiclight emitting element is overlapped with a light emitting region of thered organic light emitting element, and wherein a light emitting regionof either the green organic light emitting element or the white organiclight emitting element is overlapped with a light emitting region ofeither the green organic light emitting element or the white organiclight emitting element.
 21. The display device according to claim 1,wherein a blue organic light emitting element and either a green organiclight emitting element or a white organic light emitting element areprovided over the first substrate, wherein a red organic light emittingelement and either the green organic light emitting element or the whiteorganic light emitting element are provided over the second substrate,wherein a light emitting region of the blue organic light emittingelement is overlapped with a light emitting region of either the greenorganic light emitting element or the white organic light emittingelement, and wherein a light emitting region of either the green organiclight emitting element or the white organic light emitting element isoverlapped with a light emitting region of the red organic lightemitting element.
 22. The display device according to claim 1, wherein ablue organic light emitting element and either a green organic lightemitting element or a white organic light emitting element are providedover the first substrate, wherein a red organic light emitting elementand either the green organic light emitting element or the white organiclight emitting element are provided over the second substrate, wherein alight emitting region of the blue organic light emitting element isoverlapped with a light emitting region of the red organic lightemitting element and a light emitting region of either the green organiclight emitting element or the white organic light emitting element, andwherein a light emitting region of either the green organic lightemitting element or the white organic light emitting element isoverlapped with the light emitting region of the red organic lightemitting element and a light emitting region of either the green organiclight emitting element or the white organic light emitting element. 23.The display device according to claim 1, wherein a red organic lightemitting element, a green organic light emitting element, and a blueorganic light emitting element are provided over the first substrate,and one to three colored organic light emitting elements selected fromcomplementary colors of red, green, and blue is/are provided over thesecond substrate.
 24. The display device according to claim 1, whereinone to three organic light emitting elements selected from complementarycolors of red, green, and blue is/are formed over the first substrate,and wherein a red organic light emitting element, a green organic lightemitting element, and a blue organic light emitting element are providedover the second substrate.
 25. The display device according to claim 1,wherein a red organic light emitting element is provided over the firstsubstrate, wherein a blue organic light emitting element is providedover the second substrate, wherein a green organic light emittingelement is provided over one of the first and second substrates, andwherein a one colored organic light emitting element selected fromcomplementary colors of red, green, and blue is provided over the otherof the first substrate and the second substrate.
 26. The display deviceaccording to claim 1, wherein a blue organic light emitting element isprovided over the first substrate, wherein a red organic light emittingelement is provided over the second substrate, wherein a green organiclight emitting element is provided over one of the first and secondsubstrates, and wherein a one colored organic light emitting elementselected from complementary colors of red, green, and blue is providedover the other of the first substrate and the second substrate.
 27. Thedisplay device according to claim 1, wherein a red organic lightemitting element is provided over the first substrate, wherein a blueorganic light emitting element is provided over the second substrate,wherein a green organic light emitting element is provided over one ofthe first and second substrates, wherein a one colored organic lightemitting element selected from complementary colors of red, green, andblue is provided over the other of the first and second substrates, andwherein areas of light emitting regions of the red and blue organiclight emitting elements are larger than an area of a light emittingregion of the green organic light emitting element.
 28. The displaydevice according to claim 1, wherein a blue organic light emittingelement is provided over the first substrate, wherein a red organiclight emitting element is provided over the second substrate, wherein agreen organic light emitting element is provided over one of the firstand second substrates, wherein a one colored organic light emittingelement selected from complementary colors of red, green, and blue isprovided over the other of the first and second substrates, and whereinareas of light emitting regions of the red and blue organic lightemitting elements are larger than an area of a light emitting region ofthe green organic light emitting element.
 29. The display deviceaccording to claim 1, wherein a red organic light emitting element, agreen organic light emitting element, and a blue organic light emittingelement are provided over the first substrate, wherein a red organiclight emitting element, a green organic light emitting element, and ablue organic light emitting element are provided over the secondsubstrate, and wherein the same colored organic light emitting elementsprovided over the first and second substrates are at least partlyoverlapped with one another.
 30. The display device according to claim1, wherein a red organic light emitting element, a green organic lightemitting element, and a blue organic light emitting element are providedover the first substrate, wherein a red organic light emitting element,a green organic light emitting element, and a blue organic lightemitting element are provided over the second substrate, and wherein thedifferent colored organic light emitting elements provided over thefirst and second substrates are at least partly overlapped with oneanother.
 31. The display device according to claim 1, wherein a redorganic light emitting element, a green organic light emitting element,and a blue organic light emitting element are provided over the firstsubstrate, and wherein a blue organic light emitting element is providedover the second substrate.
 32. The display device according to claim 1,wherein a blue organic light emitting element is provided over the firstsubstrate, and wherein a red organic light emitting element, a greenorganic light emitting element, and a blue organic light emittingelement are provided over the second substrate.